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2014-07-31tracing: Fix wraparound problems in "uptime" trace clockTony Luck
commit 58d4e21e50ff3cc57910a8abc20d7e14375d2f61 upstream. The "uptime" trace clock added in: commit 8aacf017b065a805d27467843490c976835eb4a5 tracing: Add "uptime" trace clock that uses jiffies has wraparound problems when the system has been up more than 1 hour 11 minutes and 34 seconds. It converts jiffies to nanoseconds using: (u64)jiffies_to_usecs(jiffy) * 1000ULL but since jiffies_to_usecs() only returns a 32-bit value, it truncates at 2^32 microseconds. An additional problem on 32-bit systems is that the argument is "unsigned long", so fixing the return value only helps until 2^32 jiffies (49.7 days on a HZ=1000 system). Avoid these problems by using jiffies_64 as our basis, and not converting to nanoseconds (we do convert to clock_t because user facing API must not be dependent on internal kernel HZ values). Link: http://lkml.kernel.org/p/99d63c5bfe9b320a3b428d773825a37095bf6a51.1405708254.git.tony.luck@intel.com Fixes: 8aacf017b065 "tracing: Add "uptime" trace clock that uses jiffies" Signed-off-by: Tony Luck <tony.luck@intel.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-07-28ring-buffer: Fix polling on trace_pipeMartin Lau
commit 97b8ee845393701edc06e27ccec2876ff9596019 upstream. ring_buffer_poll_wait() should always put the poll_table to its wait_queue even there is immediate data available. Otherwise, the following epoll and read sequence will eventually hang forever: 1. Put some data to make the trace_pipe ring_buffer read ready first 2. epoll_ctl(efd, EPOLL_CTL_ADD, trace_pipe_fd, ee) 3. epoll_wait() 4. read(trace_pipe_fd) till EAGAIN 5. Add some more data to the trace_pipe ring_buffer 6. epoll_wait() -> this epoll_wait() will block forever ~ During the epoll_ctl(efd, EPOLL_CTL_ADD,...) call in step 2, ring_buffer_poll_wait() returns immediately without adding poll_table, which has poll_table->_qproc pointing to ep_poll_callback(), to its wait_queue. ~ During the epoll_wait() call in step 3 and step 6, ring_buffer_poll_wait() cannot add ep_poll_callback() to its wait_queue because the poll_table->_qproc is NULL and it is how epoll works. ~ When there is new data available in step 6, ring_buffer does not know it has to call ep_poll_callback() because it is not in its wait queue. Hence, block forever. Other poll implementation seems to call poll_wait() unconditionally as the very first thing to do. For example, tcp_poll() in tcp.c. Link: http://lkml.kernel.org/p/20140610060637.GA14045@devbig242.prn2.facebook.com Fixes: 2a2cc8f7c4d0 "ftrace: allow the event pipe to be polled" Reviewed-by: Chris Mason <clm@fb.com> Signed-off-by: Martin Lau <kafai@fb.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-07-28tracing: Add TRACE_ITER_PRINTK flag check in __trace_puts/__trace_bputszhangwei(Jovi)
commit f0160a5a2912267c02cfe692eac955c360de5fdf upstream. The TRACE_ITER_PRINTK check in __trace_puts/__trace_bputs is missing, so add it, to be consistent with __trace_printk/__trace_bprintk. Those functions are all called by the same function: trace_printk(). Link: http://lkml.kernel.org/p/51E7A7D6.8090900@huawei.com Signed-off-by: zhangwei(Jovi) <jovi.zhangwei@huawei.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-07-28tracing: Add ftrace_trace_stack into __trace_puts/__trace_bputszhangwei(Jovi)
commit 8abfb8727f4a724d31f9ccfd8013fbd16d539445 upstream. Currently trace option stacktrace is not applicable for trace_printk with constant string argument, the reason is in __trace_puts/__trace_bputs ftrace_trace_stack is missing. In contrast, when using trace_printk with non constant string argument(will call into __trace_printk/__trace_bprintk), then trace option stacktrace is workable, this inconstant result will confuses users a lot. Link: http://lkml.kernel.org/p/51E7A7C9.9040401@huawei.com Signed-off-by: zhangwei(Jovi) <jovi.zhangwei@huawei.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-07-28tracing: Fix graph tracer with stack tracer on other archsSteven Rostedt (Red Hat)
commit 5f8bf2d263a20b986225ae1ed7d6759dc4b93af9 upstream. Running my ftrace tests on PowerPC, it failed the test that checks if function_graph tracer is affected by the stack tracer. It was. Looking into this, I found that the update_function_graph_func() must be called even if the trampoline function is not changed. This is because archs like PowerPC do not support ftrace_ops being passed by assembly and instead uses a helper function (what the trampoline function points to). Since this function is not changed even when multiple ftrace_ops are added to the code, the test that falls out before calling update_function_graph_func() will miss that the update must still be done. Call update_function_graph_function() for all calls to update_ftrace_function() Signed-off-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-07-28tracing: instance_rmdir() leaks ftrace_event_file->filterOleg Nesterov
commit 2448e3493cb3874baa90725c87869455ebf11cd2 upstream. instance_rmdir() path destroys the event files but forgets to free file->filter. Change remove_event_file_dir() to free_event_filter(). Link: http://lkml.kernel.org/p/20140711190638.GA19517@redhat.com Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Cc: Tom Zanussi <tom.zanussi@linux.intel.com> Cc: "zhangwei(Jovi)" <jovi.zhangwei@huawei.com> Fixes: f6a84bdc75b5 "tracing: Introduce remove_event_file_dir()" Signed-off-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-07-17ring-buffer: Check if buffer exists before pollingSteven Rostedt (Red Hat)
commit 8b8b36834d0fff67fc8668093f4312dd04dcf21d upstream. The per_cpu buffers are created one per possible CPU. But these do not mean that those CPUs are online, nor do they even exist. With the addition of the ring buffer polling, it assumes that the caller polls on an existing buffer. But this is not the case if the user reads trace_pipe from a CPU that does not exist, and this causes the kernel to crash. Simple fix is to check the cpu against buffer bitmask against to see if the buffer was allocated or not and return -ENODEV if it is not. More updates were done to pass the -ENODEV back up to userspace. Link: http://lkml.kernel.org/r/5393DB61.6060707@oracle.com Reported-by: Sasha Levin <sasha.levin@oracle.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-07-09tracing/uprobes: Fix the usage of uprobe_buffer_enable() in probe_event_enable()Oleg Nesterov
commit fb6bab6a5ad46d00b5ffa22268f21df1cd7c59df upstream. The usage of uprobe_buffer_enable() added by dcad1a20 is very wrong, 1. uprobe_buffer_enable() and uprobe_buffer_disable() are not balanced, _enable() should be called only if !enabled. 2. If uprobe_buffer_enable() fails probe_event_enable() should clear tp.flags and free event_file_link. 3. If uprobe_register() fails it should do uprobe_buffer_disable(). Link: http://lkml.kernel.org/p/20140627170146.GA18332@redhat.com Acked-by: Namhyung Kim <namhyung@kernel.org> Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Reviewed-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Fixes: dcad1a204f72 "tracing/uprobes: Fetch args before reserving a ring buffer" Signed-off-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-07-09tracing/uprobes: Revert "Support mix of ftrace and perf"Oleg Nesterov
commit 48212542067a7ff6cbe829dbae279c2ff7557b44 upstream. This reverts commit 43fe98913c9f67e3b523615ee3316f9520a623e0. This patch is very wrong. Firstly, this change leads to unbalanced uprobe_unregister(). Just for example, # perf probe -x /lib/libc.so.6 syscall # echo 1 >> /sys/kernel/debug/tracing/events/probe_libc/enable # perf record -e probe_libc:syscall whatever after that uprobe is dead (unregistered) but the user of ftrace/perf can't know this, and it looks as if nobody hits this probe. This would be easy to fix, but there are other reasons why it is not simple to mix ftrace and perf. If nothing else, they can't share the same ->consumer.filter. This is fixable too, but probably we need to fix the poorly designed uprobe_register() interface first. At least "register" and "apply" should be clearly separated. Link: http://lkml.kernel.org/p/20140627170136.GA18319@redhat.com Cc: Tom Zanussi <tom.zanussi@linux.intel.com> Cc: "zhangwei(Jovi)" <jovi.zhangwei@huawei.com> Acked-by: Namhyung Kim <namhyung@kernel.org> Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Reviewed-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Signed-off-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-07-09tracing: Remove ftrace_stop/start() from reading the trace fileSteven Rostedt (Red Hat)
commit 099ed151675cd1d2dbeae1dac697975f6a68716d upstream. Disabling reading and writing to the trace file should not be able to disable all function tracing callbacks. There's other users today (like kprobes and perf). Reading a trace file should not stop those from happening. Reviewed-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-07-06tracing: Try again for saved cmdline if failed due to lockingSteven Rostedt (Red Hat)
commit 379cfdac37923653c9d4242d10052378b7563005 upstream. In order to prevent the saved cmdline cache from being filled when tracing is not active, the comms are only recorded after a trace event is recorded. The problem is, a comm can fail to be recorded if the trace_cmdline_lock is held. That lock is taken via a trylock to allow it to happen from any context (including NMI). If the lock fails to be taken, the comm is skipped. No big deal, as we will try again later. But! Because of the code that was added to only record after an event, we may not try again later as the recording is made as a oneshot per event per CPU. Only disable the recording of the comm if the comm is actually recorded. Fixes: 7ffbd48d5cab "tracing: Cache comms only after an event occurred" Signed-off-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-05-02tracing: Use rcu_dereference_sched() for trace event triggersSteven Rostedt (Red Hat)
As trace event triggers are now part of the mainline kernel, I added my trace event trigger tests to my test suite I run on all my kernels. Now these tests get run under different config options, and one of those options is CONFIG_PROVE_RCU, which checks under lockdep that the rcu locking primitives are being used correctly. This triggered the following splat: =============================== [ INFO: suspicious RCU usage. ] 3.15.0-rc2-test+ #11 Not tainted ------------------------------- kernel/trace/trace_events_trigger.c:80 suspicious rcu_dereference_check() usage! other info that might help us debug this: rcu_scheduler_active = 1, debug_locks = 0 4 locks held by swapper/1/0: #0: ((&(&j_cdbs->work)->timer)){..-...}, at: [<ffffffff8104d2cc>] call_timer_fn+0x5/0x1be #1: (&(&pool->lock)->rlock){-.-...}, at: [<ffffffff81059856>] __queue_work+0x140/0x283 #2: (&p->pi_lock){-.-.-.}, at: [<ffffffff8106e961>] try_to_wake_up+0x2e/0x1e8 #3: (&rq->lock){-.-.-.}, at: [<ffffffff8106ead3>] try_to_wake_up+0x1a0/0x1e8 stack backtrace: CPU: 1 PID: 0 Comm: swapper/1 Not tainted 3.15.0-rc2-test+ #11 Hardware name: /DG965MQ, BIOS MQ96510J.86A.0372.2006.0605.1717 06/05/2006 0000000000000001 ffff88007e083b98 ffffffff819f53a5 0000000000000006 ffff88007b0942c0 ffff88007e083bc8 ffffffff81081307 ffff88007ad96d20 0000000000000000 ffff88007af2d840 ffff88007b2e701c ffff88007e083c18 Call Trace: <IRQ> [<ffffffff819f53a5>] dump_stack+0x4f/0x7c [<ffffffff81081307>] lockdep_rcu_suspicious+0x107/0x110 [<ffffffff810ee51c>] event_triggers_call+0x99/0x108 [<ffffffff810e8174>] ftrace_event_buffer_commit+0x42/0xa4 [<ffffffff8106aadc>] ftrace_raw_event_sched_wakeup_template+0x71/0x7c [<ffffffff8106bcbf>] ttwu_do_wakeup+0x7f/0xff [<ffffffff8106bd9b>] ttwu_do_activate.constprop.126+0x5c/0x61 [<ffffffff8106eadf>] try_to_wake_up+0x1ac/0x1e8 [<ffffffff8106eb77>] wake_up_process+0x36/0x3b [<ffffffff810575cc>] wake_up_worker+0x24/0x26 [<ffffffff810578bc>] insert_work+0x5c/0x65 [<ffffffff81059982>] __queue_work+0x26c/0x283 [<ffffffff81059999>] ? __queue_work+0x283/0x283 [<ffffffff810599b7>] delayed_work_timer_fn+0x1e/0x20 [<ffffffff8104d3a6>] call_timer_fn+0xdf/0x1be^M [<ffffffff8104d2cc>] ? call_timer_fn+0x5/0x1be [<ffffffff81059999>] ? __queue_work+0x283/0x283 [<ffffffff8104d823>] run_timer_softirq+0x1a4/0x22f^M [<ffffffff8104696d>] __do_softirq+0x17b/0x31b^M [<ffffffff81046d03>] irq_exit+0x42/0x97 [<ffffffff81a08db6>] smp_apic_timer_interrupt+0x37/0x44 [<ffffffff81a07a2f>] apic_timer_interrupt+0x6f/0x80 <EOI> [<ffffffff8100a5d8>] ? default_idle+0x21/0x32 [<ffffffff8100a5d6>] ? default_idle+0x1f/0x32 [<ffffffff8100ac10>] arch_cpu_idle+0xf/0x11 [<ffffffff8107b3a4>] cpu_startup_entry+0x1a3/0x213 [<ffffffff8102a23c>] start_secondary+0x212/0x219 The cause is that the triggers are protected by rcu_read_lock_sched() but the data is dereferenced with rcu_dereference() which expects it to be protected with rcu_read_lock(). The proper reference should be rcu_dereference_sched(). Cc: Tom Zanussi <tom.zanussi@linux.intel.com> Cc: stable@vger.kernel.org # 3.14+ Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2014-04-28ftrace/module: Hardcode ftrace_module_init() call into load_module()Steven Rostedt (Red Hat)
A race exists between module loading and enabling of function tracer. CPU 1 CPU 2 ----- ----- load_module() module->state = MODULE_STATE_COMING register_ftrace_function() mutex_lock(&ftrace_lock); ftrace_startup() update_ftrace_function(); ftrace_arch_code_modify_prepare() set_all_module_text_rw(); <enables-ftrace> ftrace_arch_code_modify_post_process() set_all_module_text_ro(); [ here all module text is set to RO, including the module that is loading!! ] blocking_notifier_call_chain(MODULE_STATE_COMING); ftrace_init_module() [ tries to modify code, but it's RO, and fails! ftrace_bug() is called] When this race happens, ftrace_bug() will produces a nasty warning and all of the function tracing features will be disabled until reboot. The simple solution is to treate module load the same way the core kernel is treated at boot. To hardcode the ftrace function modification of converting calls to mcount into nops. This is done in init/main.c there's no reason it could not be done in load_module(). This gives a better control of the changes and doesn't tie the state of the module to its notifiers as much. Ftrace is special, it needs to be treated as such. The reason this would work, is that the ftrace_module_init() would be called while the module is in MODULE_STATE_UNFORMED, which is ignored by the set_all_module_text_ro() call. Link: http://lkml.kernel.org/r/1395637826-3312-1-git-send-email-indou.takao@jp.fujitsu.com Reported-by: Takao Indoh <indou.takao@jp.fujitsu.com> Acked-by: Rusty Russell <rusty@rustcorp.com.au> Cc: stable@vger.kernel.org # 2.6.38+ Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2014-04-18Merge tag 'trace-fixes-v3.15-rc1' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace Pull tracing fixes from Steven Rostedt: "This contains two fixes. The first is to remove a duplication of creating debugfs files that already exist and causes an error report to be printed due to the failure of the second creation. The second is a memory leak fix that was introduced in 3.14" * tag 'trace-fixes-v3.15-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: tracing/uprobes: Fix uprobe_cpu_buffer memory leak tracing: Do not try to recreated toplevel set_ftrace_* files
2014-04-17tracing/uprobes: Fix uprobe_cpu_buffer memory leakzhangwei(Jovi)
Forgot to free uprobe_cpu_buffer percpu page in uprobe_buffer_disable(). Link: http://lkml.kernel.org/p/534F8B3F.1090407@huawei.com Cc: stable@vger.kernel.org # v3.14+ Acked-by: Namhyung Kim <namhyung@kernel.org> Signed-off-by: zhangwei(Jovi) <jovi.zhangwei@huawei.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2014-04-16tracing: Do not try to recreated toplevel set_ftrace_* filesSteven Rostedt (Red Hat)
With the restructing of the function tracer working with instances, the "top level" buffer is a bit special, as the function tracing is mapped to the same set of filters. This is done by using a "global_ops" descriptor and having the "set_ftrace_filter" and "set_ftrace_notrace" map to it. When an instance is created, it creates the same files but its for the local instance and not the global_ops. The issues is that the local instance creation shares some code with the global instance one and we end up trying to create th top level "set_ftrace_*" files twice, and on boot up, we get an error like this: Could not create debugfs 'set_ftrace_filter' entry Could not create debugfs 'set_ftrace_notrace' entry The reason they failed to be created was because they were created twice, and the second time gives this error as you can not create the same file twice. Reported-by: Borislav Petkov <bp@alien8.de> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2014-04-12Merge branch 'for-linus' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs Pull vfs updates from Al Viro: "The first vfs pile, with deep apologies for being very late in this window. Assorted cleanups and fixes, plus a large preparatory part of iov_iter work. There's a lot more of that, but it'll probably go into the next merge window - it *does* shape up nicely, removes a lot of boilerplate, gets rid of locking inconsistencie between aio_write and splice_write and I hope to get Kent's direct-io rewrite merged into the same queue, but some of the stuff after this point is having (mostly trivial) conflicts with the things already merged into mainline and with some I want more testing. This one passes LTP and xfstests without regressions, in addition to usual beating. BTW, readahead02 in ltp syscalls testsuite has started giving failures since "mm/readahead.c: fix readahead failure for memoryless NUMA nodes and limit readahead pages" - might be a false positive, might be a real regression..." * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (63 commits) missing bits of "splice: fix racy pipe->buffers uses" cifs: fix the race in cifs_writev() ceph_sync_{,direct_}write: fix an oops on ceph_osdc_new_request() failure kill generic_file_buffered_write() ocfs2_file_aio_write(): switch to generic_perform_write() ceph_aio_write(): switch to generic_perform_write() xfs_file_buffered_aio_write(): switch to generic_perform_write() export generic_perform_write(), start getting rid of generic_file_buffer_write() generic_file_direct_write(): get rid of ppos argument btrfs_file_aio_write(): get rid of ppos kill the 5th argument of generic_file_buffered_write() kill the 4th argument of __generic_file_aio_write() lustre: don't open-code kernel_recvmsg() ocfs2: don't open-code kernel_recvmsg() drbd: don't open-code kernel_recvmsg() constify blk_rq_map_user_iov() and friends lustre: switch to kernel_sendmsg() ocfs2: don't open-code kernel_sendmsg() take iov_iter stuff to mm/iov_iter.c process_vm_access: tidy up a bit ...
2014-04-12Merge tag 'trace-3.15-v2' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace Pull more tracing updates from Steven Rostedt: "This includes the final patch to clean up and fix the issue with the design of tracepoints and how a user could register a tracepoint and have that tracepoint not be activated but no error was shown. The design was for an out of tree module but broke in tree users. The clean up was to remove the saving of the hash table of tracepoint names such that they can be enabled before they exist (enabling a module tracepoint before that module is loaded). This added more complexity than needed. The clean up was to remove that code and just enable tracepoints that exist or fail if they do not. This removed a lot of code as well as the complexity that it brought. As a side effect, instead of registering a tracepoint by its name, the tracepoint needs to be registered with the tracepoint descriptor. This removes having to duplicate the tracepoint names that are enabled. The second patch was added that simplified the way modules were searched for. This cleanup required changes that were in the 3.15 queue as well as some changes that were added late in the 3.14-rc cycle. This final change waited till the two were merged in upstream and then the change was added and full tests were run. Unfortunately, the test found some errors, but after it was already submitted to the for-next branch and not to be rebased. Sparse errors were detected by Fengguang Wu's bot tests, and my internal tests discovered that the anonymous union initialization triggered a bug in older gcc compilers. Luckily, there was a bugzilla for the gcc bug which gave a work around to the problem. The third and fourth patch handled the sparse error and the gcc bug respectively. A final patch was tagged along to fix a missing documentation for the README file" * tag 'trace-3.15-v2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: tracing: Add missing function triggers dump and cpudump to README tracing: Fix anonymous unions in struct ftrace_event_call tracepoint: Fix sparse warnings in tracepoint.c tracepoint: Simplify tracepoint module search tracepoint: Use struct pointer instead of name hash for reg/unreg tracepoints
2014-04-12missing bits of "splice: fix racy pipe->buffers uses"Al Viro
that commit has fixed only the parts of that mess in fs/splice.c itself; there had been more in several other ->splice_read() instances... Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2014-04-10tracing: Add missing function triggers dump and cpudump to READMESteven Rostedt (Red Hat)
The debugfs tracing README file lists all the function triggers except for dump and cpudump. These should be added too. Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2014-04-09tracing: Fix anonymous unions in struct ftrace_event_callMathieu Desnoyers
gcc <= 4.5.x has significant limitations with respect to initialization of anonymous unions within structures. They need to be surrounded by brackets, _and_ they need to be initialized in the same order in which they appear in the structure declaration. Link: http://gcc.gnu.org/bugzilla/show_bug.cgi?id=10676 Link: http://lkml.kernel.org/r/1397077568-3156-1-git-send-email-mathieu.desnoyers@efficios.com Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2014-04-08tracepoint: Use struct pointer instead of name hash for reg/unreg tracepointsMathieu Desnoyers
Register/unregister tracepoint probes with struct tracepoint pointer rather than tracepoint name. This change, which vastly simplifies tracepoint.c, has been proposed by Steven Rostedt. It also removes 8.8kB (mostly of text) to the vmlinux size. From this point on, the tracers need to pass a struct tracepoint pointer to probe register/unregister. A probe can now only be connected to a tracepoint that exists. Moreover, tracers are responsible for unregistering the probe before the module containing its associated tracepoint is unloaded. text data bss dec hex filename 10443444 4282528 10391552 25117524 17f4354 vmlinux.orig 10434930 4282848 10391552 25109330 17f2352 vmlinux Link: http://lkml.kernel.org/r/1396992381-23785-2-git-send-email-mathieu.desnoyers@efficios.com CC: Ingo Molnar <mingo@kernel.org> CC: Frederic Weisbecker <fweisbec@gmail.com> CC: Andrew Morton <akpm@linux-foundation.org> CC: Frank Ch. Eigler <fche@redhat.com> CC: Johannes Berg <johannes.berg@intel.com> Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> [ SDR - fixed return val in void func in tracepoint_module_going() ] Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2014-04-07Merge branch 'akpm' (incoming from Andrew)Linus Torvalds
Merge second patch-bomb from Andrew Morton: - the rest of MM - zram updates - zswap updates - exit - procfs - exec - wait - crash dump - lib/idr - rapidio - adfs, affs, bfs, ufs - cris - Kconfig things - initramfs - small amount of IPC material - percpu enhancements - early ioremap support - various other misc things * emailed patches from Andrew Morton <akpm@linux-foundation.org>: (156 commits) MAINTAINERS: update Intel C600 SAS driver maintainers fs/ufs: remove unused ufs_super_block_third pointer fs/ufs: remove unused ufs_super_block_second pointer fs/ufs: remove unused ufs_super_block_first pointer fs/ufs/super.c: add __init to init_inodecache() doc/kernel-parameters.txt: add early_ioremap_debug arm64: add early_ioremap support arm64: initialize pgprot info earlier in boot x86: use generic early_ioremap mm: create generic early_ioremap() support x86/mm: sparse warning fix for early_memremap lglock: map to spinlock when !CONFIG_SMP percpu: add preemption checks to __this_cpu ops vmstat: use raw_cpu_ops to avoid false positives on preemption checks slub: use raw_cpu_inc for incrementing statistics net: replace __this_cpu_inc in route.c with raw_cpu_inc modules: use raw_cpu_write for initialization of per cpu refcount. mm: use raw_cpu ops for determining current NUMA node percpu: add raw_cpu_ops slub: fix leak of 'name' in sysfs_slab_add ...
2014-04-07kernel: use macros from compiler.h instead of __attribute__((...))Gideon Israel Dsouza
To increase compiler portability there is <linux/compiler.h> which provides convenience macros for various gcc constructs. Eg: __weak for __attribute__((weak)). I've replaced all instances of gcc attributes with the right macro in the kernel subsystem. Signed-off-by: Gideon Israel Dsouza <gidisrael@gmail.com> Cc: "Rafael J. Wysocki" <rjw@sisk.pl> Cc: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-04-07Merge tag 'cpu-hotplug-3.15-rc1' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm Pull CPU hotplug notifiers registration fixes from Rafael Wysocki: "The purpose of this single series of commits from Srivatsa S Bhat (with a small piece from Gautham R Shenoy) touching multiple subsystems that use CPU hotplug notifiers is to provide a way to register them that will not lead to deadlocks with CPU online/offline operations as described in the changelog of commit 93ae4f978ca7f ("CPU hotplug: Provide lockless versions of callback registration functions"). The first three commits in the series introduce the API and document it and the rest simply goes through the users of CPU hotplug notifiers and converts them to using the new method" * tag 'cpu-hotplug-3.15-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm: (52 commits) net/iucv/iucv.c: Fix CPU hotplug callback registration net/core/flow.c: Fix CPU hotplug callback registration mm, zswap: Fix CPU hotplug callback registration mm, vmstat: Fix CPU hotplug callback registration profile: Fix CPU hotplug callback registration trace, ring-buffer: Fix CPU hotplug callback registration xen, balloon: Fix CPU hotplug callback registration hwmon, via-cputemp: Fix CPU hotplug callback registration hwmon, coretemp: Fix CPU hotplug callback registration thermal, x86-pkg-temp: Fix CPU hotplug callback registration octeon, watchdog: Fix CPU hotplug callback registration oprofile, nmi-timer: Fix CPU hotplug callback registration intel-idle: Fix CPU hotplug callback registration clocksource, dummy-timer: Fix CPU hotplug callback registration drivers/base/topology.c: Fix CPU hotplug callback registration acpi-cpufreq: Fix CPU hotplug callback registration zsmalloc: Fix CPU hotplug callback registration scsi, fcoe: Fix CPU hotplug callback registration scsi, bnx2fc: Fix CPU hotplug callback registration scsi, bnx2i: Fix CPU hotplug callback registration ...
2014-04-05Merge branch 'for-linus' of git://ftp.arm.linux.org.uk/~rmk/linux-armLinus Torvalds
Pull ARM changes from Russell King: - Perf updates from Will Deacon: - Support for Qualcomm Krait processors (run perf on your phone!) - Support for Cortex-A12 (run perf stat on your FPGA!) - Support for perf_sample_event_took, allowing us to automatically decrease the sample rate if we can't handle the PMU interrupts quickly enough (run perf record on your FPGA!). - Basic uprobes support from David Long: This patch series adds basic uprobes support to ARM. It is based on patches developed earlier by Rabin Vincent. That approach of adding hooks into the kprobes instruction parsing code was not well received. This approach separates the ARM instruction parsing code in kprobes out into a separate set of functions which can be used by both kprobes and uprobes. Both kprobes and uprobes then provide their own semantic action tables to process the results of the parsing. - ARMv7M (microcontroller) updates from Uwe Kleine-König - OMAP DMA updates (recently added Vinod's Ack even though they've been sitting in linux-next for a few months) to reduce the reliance of omap-dma on the code in arch/arm. - SA11x0 changes from Dmitry Eremin-Solenikov and Alexander Shiyan - Support for Cortex-A12 CPU - Align support for ARMv6 with ARMv7 so they can cooperate better in a single zImage. - Addition of first AT_HWCAP2 feature bits for ARMv8 crypto support. - Removal of IRQ_DISABLED from various ARM files - Improved efficiency of virt_to_page() for single zImage - Patch from Ulf Hansson to permit runtime PM callbacks to be available for AMBA devices for suspend/resume as well. - Finally kill asm/system.h on ARM. * 'for-linus' of git://ftp.arm.linux.org.uk/~rmk/linux-arm: (89 commits) dmaengine: omap-dma: more consolidation of CCR register setup dmaengine: omap-dma: move IRQ handling to omap-dma dmaengine: omap-dma: move register read/writes into omap-dma.c ARM: omap: dma: get rid of 'p' allocation and clean up ARM: omap: move dma channel allocation into plat-omap code ARM: omap: dma: get rid of errata global ARM: omap: clean up DMA register accesses ARM: omap: remove almost-const variables ARM: omap: remove references to disable_irq_lch dmaengine: omap-dma: cleanup errata 3.3 handling dmaengine: omap-dma: provide register read/write functions dmaengine: omap-dma: use cached CCR value when enabling DMA dmaengine: omap-dma: move barrier to omap_dma_start_desc() dmaengine: omap-dma: move clnk_ctrl setting to preparation functions dmaengine: omap-dma: improve efficiency loading C.SA/C.EI/C.FI registers dmaengine: omap-dma: consolidate clearing channel status register dmaengine: omap-dma: move CCR buffering disable errata out of the fast path dmaengine: omap-dma: provide register definitions dmaengine: omap-dma: consolidate setup of CCR dmaengine: omap-dma: consolidate setup of CSDP ...
2014-04-03Merge tag 'trace-3.15' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace Pull tracing updates from Steven Rostedt: "Most of the changes were largely clean ups, and some documentation. But there were a few features that were added: Uprobes now work with event triggers and multi buffers and have support under ftrace and perf. The big feature is that the function tracer can now be used within the multi buffer instances. That is, you can now trace some functions in one buffer, others in another buffer, all functions in a third buffer and so on. They are basically agnostic from each other. This only works for the function tracer and not for the function graph trace, although you can have the function graph tracer running in the top level buffer (or any tracer for that matter) and have different function tracing going on in the sub buffers" * tag 'trace-3.15' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: (45 commits) tracing: Add BUG_ON when stack end location is over written tracepoint: Remove unused API functions Revert "tracing: Move event storage for array from macro to standalone function" ftrace: Constify ftrace_text_reserved tracepoints: API doc update to tracepoint_probe_register() return value tracepoints: API doc update to data argument ftrace: Fix compilation warning about control_ops_free ftrace/x86: BUG when ftrace recovery fails ftrace: Warn on error when modifying ftrace function ftrace: Remove freelist from struct dyn_ftrace ftrace: Do not pass data to ftrace_dyn_arch_init ftrace: Pass retval through return in ftrace_dyn_arch_init() ftrace: Inline the code from ftrace_dyn_table_alloc() ftrace: Cleanup of global variables ftrace_new_pgs and ftrace_update_cnt tracing: Evaluate len expression only once in __dynamic_array macro tracing: Correctly expand len expressions from __dynamic_array macro tracing/module: Replace include of tracepoint.h with jump_label.h in module.h tracing: Fix event header migrate.h to include tracepoint.h tracing: Fix event header writeback.h to include tracepoint.h tracing: Warn if a tracepoint is not set via debugfs ...
2014-04-01pipe: kill ->map() and ->unmap()Al Viro
all pipe_buffer_operations have the same instances of those... Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2014-04-01Merge branch 'for-3.15/core' of git://git.kernel.dk/linux-blockLinus Torvalds
Pull core block layer updates from Jens Axboe: "This is the pull request for the core block IO bits for the 3.15 kernel. It's a smaller round this time, it contains: - Various little blk-mq fixes and additions from Christoph and myself. - Cleanup of the IPI usage from the block layer, and associated helper code. From Frederic Weisbecker and Jan Kara. - Duplicate code cleanup in bio-integrity from Gu Zheng. This will give you a merge conflict, but that should be easy to resolve. - blk-mq notify spinlock fix for RT from Mike Galbraith. - A blktrace partial accounting bug fix from Roman Pen. - Missing REQ_SYNC detection fix for blk-mq from Shaohua Li" * 'for-3.15/core' of git://git.kernel.dk/linux-block: (25 commits) blk-mq: add REQ_SYNC early rt,blk,mq: Make blk_mq_cpu_notify_lock a raw spinlock blk-mq: support partial I/O completions blk-mq: merge blk_mq_insert_request and blk_mq_run_request blk-mq: remove blk_mq_alloc_rq blk-mq: don't dump CPU -> hw queue map on driver load blk-mq: fix wrong usage of hctx->state vs hctx->flags blk-mq: allow blk_mq_init_commands() to return failure block: remove old blk_iopoll_enabled variable blktrace: fix accounting of partially completed requests smp: Rename __smp_call_function_single() to smp_call_function_single_async() smp: Remove wait argument from __smp_call_function_single() watchdog: Simplify a little the IPI call smp: Move __smp_call_function_single() below its safe version smp: Consolidate the various smp_call_function_single() declensions smp: Teach __smp_call_function_single() to check for offline cpus smp: Remove unused list_head from csd smp: Iterate functions through llist_for_each_entry_safe() block: Stop abusing rq->csd.list in blk-softirq block: Remove useless IPI struct initialization ...
2014-03-31Merge branch 'x86-asmlinkage-for-linus' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull x86 LTO changes from Peter Anvin: "More infrastructure work in preparation for link-time optimization (LTO). Most of these changes is to make sure symbols accessed from assembly code are properly marked as visible so the linker doesn't remove them. My understanding is that the changes to support LTO are still not upstream in binutils, but are on the way there. This patchset should conclude the x86-specific changes, and remaining patches to actually enable LTO will be fed through the Kbuild tree (other than keeping up with changes to the x86 code base, of course), although not necessarily in this merge window" * 'x86-asmlinkage-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (25 commits) Kbuild, lto: Handle basic LTO in modpost Kbuild, lto: Disable LTO for asm-offsets.c Kbuild, lto: Add a gcc-ld script to let run gcc as ld Kbuild, lto: add ld-version and ld-ifversion macros Kbuild, lto: Drop .number postfixes in modpost Kbuild, lto, workaround: Don't warn for initcall_reference in modpost lto: Disable LTO for sys_ni lto: Handle LTO common symbols in module loader lto, workaround: Add workaround for initcall reordering lto: Make asmlinkage __visible x86, lto: Disable LTO for the x86 VDSO initconst, x86: Fix initconst mistake in ts5500 code initconst: Fix initconst mistake in dcdbas asmlinkage: Make trace_hardirqs_on/off_caller visible asmlinkage, x86: Fix 32bit memcpy for LTO asmlinkage Make __stack_chk_failed and memcmp visible asmlinkage: Mark rwsem functions that can be called from assembler asmlinkage asmlinkage: Make main_extable_sort_needed visible asmlinkage, mutex: Mark __visible asmlinkage: Make trace_hardirq visible ...
2014-03-31Merge branch 'sched-core-for-linus' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull scheduler changes from Ingo Molnar: "Bigger changes: - sched/idle restructuring: they are WIP preparation for deeper integration between the scheduler and idle state selection, by Nicolas Pitre. - add NUMA scheduling pseudo-interleaving, by Rik van Riel. - optimize cgroup context switches, by Peter Zijlstra. - RT scheduling enhancements, by Thomas Gleixner. The rest is smaller changes, non-urgnt fixes and cleanups" * 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (68 commits) sched: Clean up the task_hot() function sched: Remove double calculation in fix_small_imbalance() sched: Fix broken setscheduler() sparc64, sched: Remove unused sparc64_multi_core sched: Remove unused mc_capable() and smt_capable() sched/numa: Move task_numa_free() to __put_task_struct() sched/fair: Fix endless loop in idle_balance() sched/core: Fix endless loop in pick_next_task() sched/fair: Push down check for high priority class task into idle_balance() sched/rt: Fix picking RT and DL tasks from empty queue trace: Replace hardcoding of 19 with MAX_NICE sched: Guarantee task priority in pick_next_task() sched/idle: Remove stale old file sched: Put rq's sched_avg under CONFIG_FAIR_GROUP_SCHED cpuidle/arm64: Remove redundant cpuidle_idle_call() cpuidle/powernv: Remove redundant cpuidle_idle_call() sched, nohz: Exclude isolated cores from load balancing sched: Fix select_task_rq_fair() description comments workqueue: Replace hardcoding of -20 and 19 with MIN_NICE and MAX_NICE sys: Replace hardcoding of -20 and 19 with MIN_NICE and MAX_NICE ...
2014-03-31Merge branch 'perf-core-for-linus' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull perf changes from Ingo Molnar: "Main changes: Kernel side changes: - Add SNB/IVB/HSW client uncore memory controller support (Stephane Eranian) - Fix various x86/P4 PMU driver bugs (Don Zickus) Tooling, user visible changes: - Add several futex 'perf bench' microbenchmarks (Davidlohr Bueso) - Speed up thread map generation (Don Zickus) - Introduce 'perf kvm --list-cmds' command line option for use by scripts (Ramkumar Ramachandra) - Print the evsel name in the annotate stdio output, prep to fix support outputting annotation for multiple events, not just for the first one (Arnaldo Carvalho de Melo) - Allow setting preferred callchain method in .perfconfig (Jiri Olsa) - Show in what binaries/modules 'perf probe's are set (Masami Hiramatsu) - Support distro-style debuginfo for uprobe in 'perf probe' (Masami Hiramatsu) Tooling, internal changes and fixes: - Use tid in mmap/mmap2 events to find maps (Don Zickus) - Record the reason for filtering an address_location (Namhyung Kim) - Apply all filters to an addr_location (Namhyung Kim) - Merge al->filtered with hist_entry->filtered in report/hists (Namhyung Kim) - Fix memory leak when synthesizing thread records (Namhyung Kim) - Use ui__has_annotation() in 'report' (Namhyung Kim) - hists browser refactorings to reuse code accross UIs (Namhyung Kim) - Add support for the new DWARF unwinder library in elfutils (Jiri Olsa) - Fix build race in the generation of bison files (Jiri Olsa) - Further streamline the feature detection display, trimming it a bit to show just the libraries detected, using VF=1 gets a more verbose output, showing the less interesting feature checks as well (Jiri Olsa). - Check compatible symtab type before loading dso (Namhyung Kim) - Check return value of filename__read_debuglink() (Stephane Eranian) - Move some hashing and fs related code from tools/perf/util/ to tools/lib/ so that it can be used by more tools/ living utilities (Borislav Petkov) - Prepare DWARF unwinding code for using an elfutils alternative unwinding library (Jiri Olsa) - Fix DWARF unwind max_stack processing (Jiri Olsa) - Add dwarf unwind 'perf test' entry (Jiri Olsa) - 'perf probe' improvements including memory leak fixes, sharing the intlist class with other tools, uprobes/kprobes code sharing and use of ref_reloc_sym (Masami Hiramatsu) - Shorten sample symbol resolving by adding cpumode to struct addr_location (Arnaldo Carvalho de Melo) - Fix synthesizing mmaps for threads (Don Zickus) - Fix invalid output on event group stdio report (Namhyung Kim) - Fixup header alignment in 'perf sched latency' output (Ramkumar Ramachandra) - Fix off-by-one error in 'perf timechart record' argv handling (Ramkumar Ramachandra) Tooling, cleanups: - Remove unused thread__find_map function (Jiri Olsa) - Remove unused simple_strtoul() function (Ramkumar Ramachandra) Tooling, documentation updates: - Update function names in debug messages (Ramkumar Ramachandra) - Update some code references in design.txt (Ramkumar Ramachandra) - Clarify load-latency information in the 'perf mem' docs (Andi Kleen) - Clarify x86 register naming in 'perf probe' docs (Andi Kleen)" * 'perf-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (96 commits) perf tools: Remove unused simple_strtoul() function perf tools: Update some code references in design.txt perf evsel: Update function names in debug messages perf tools: Remove thread__find_map function perf annotate: Print the evsel name in the stdio output perf report: Use ui__has_annotation() perf tools: Fix memory leak when synthesizing thread records perf tools: Use tid in mmap/mmap2 events to find maps perf report: Merge al->filtered with hist_entry->filtered perf symbols: Apply all filters to an addr_location perf symbols: Record the reason for filtering an address_location perf sched: Fixup header alignment in 'latency' output perf timechart: Fix off-by-one error in 'record' argv handling perf machine: Factor machine__find_thread to take tid argument perf tools: Speed up thread map generation perf kvm: introduce --list-cmds for use by scripts perf ui hists: Pass evsel to hpp->header/width functions explicitly perf symbols: Introduce thread__find_cpumode_addr_location perf session: Change header.misc dump from decimal to hex perf ui/tui: Reuse generic __hpp__fmt() code ...
2014-03-25tracing: Fix traceon trigger condition to actually turn tracing onSteven Rostedt (Red Hat)
While working on my tutorial for 2014 Linux Collaboration Summit I found that the traceon trigger did not work when conditions were used. The other triggers worked fine though. Looking into it, it is because of the way the triggers use the ring buffer to store the fields it will use for the condition. But if tracing is off, nothing is stored in the buffer, and the tracepoint exits before calling the trigger to test the condition. This is fine for all the triggers that only work when tracing is on, but for traceon trigger that is to work when tracing is off, nothing happens. The fix is simple, just use a temp ring buffer to record the event if tracing is off and the event has a trace event conditional trigger enabled. The rest of the tracepoint code will work just fine, but the tracepoint wont be recorded in the other buffers. Cc: Tom Zanussi <tom.zanussi@linux.intel.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2014-03-24tracing: Add BUG_ON when stack end location is over writtenAaron Tomlin
It is difficult to detect a stack overrun when it actually occurs. We have observed that this type of corruption is often silent and can go unnoticed. Once the corrupted region is examined, the outcome is undefined and often results in sporadic system crashes. When the stack tracing feature is enabled, let's check for this condition and take appropriate action. Note: init_task doesn't get its stack end location set to STACK_END_MAGIC. Link: http://lkml.kernel.org/r/1395669837-30209-1-git-send-email-atomlin@redhat.com Signed-off-by: Aaron Tomlin <atomlin@redhat.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2014-03-21Revert "tracing: Move event storage for array from macro to standalone function"Steven Rostedt (Red Hat)
I originally wrote commit 35bb4399bd0e to shrink the size of the overhead of tracepoints by several kilobytes. Later, I received a patch from Vaibhav Nagarnaik that fixed a bug in the same code that this commit touches. Not only did it fix a bug, it also removed code and shrunk the size of the overhead of trace events even more than this commit did. Since this commit is scheduled for 3.15 and Vaibhav's patch is already in mainline, I need to revert this patch in order to keep it from conflicting with Vaibhav's patch. Not to mention, Vaibhav's patch makes this patch obsolete. Link: http://lkml.kernel.org/r/20140320225637.0226041b@gandalf.local.home Cc: Vaibhav Nagarnaik <vnagarnaik@google.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2014-03-20tracing: Fix array size mismatch in format stringVaibhav Nagarnaik
In event format strings, the array size is reported in two locations. One in array subscript and then via the "size:" attribute. The values reported there have a mismatch. For e.g., in sched:sched_switch the prev_comm and next_comm character arrays have subscript values as [32] where as the actual field size is 16. name: sched_switch ID: 301 format: field:unsigned short common_type; offset:0; size:2; signed:0; field:unsigned char common_flags; offset:2; size:1; signed:0; field:unsigned char common_preempt_count; offset:3; size:1;signed:0; field:int common_pid; offset:4; size:4; signed:1; field:char prev_comm[32]; offset:8; size:16; signed:1; field:pid_t prev_pid; offset:24; size:4; signed:1; field:int prev_prio; offset:28; size:4; signed:1; field:long prev_state; offset:32; size:8; signed:1; field:char next_comm[32]; offset:40; size:16; signed:1; field:pid_t next_pid; offset:56; size:4; signed:1; field:int next_prio; offset:60; size:4; signed:1; After bisection, the following commit was blamed: 92edca0 tracing: Use direct field, type and system names This commit removes the duplication of strings for field->name and field->type assuming that all the strings passed in __trace_define_field() are immutable. This is not true for arrays, where the type string is created in event_storage variable and field->type for all array fields points to event_storage. Use __stringify() to create a string constant for the type string. Also, get rid of event_storage and event_storage_mutex that are not needed anymore. also, an added benefit is that this reduces the overhead of events a bit more: text data bss dec hex filename 8424787 2036472 1302528 11763787 b3804b vmlinux 8420814 2036408 1302528 11759750 b37086 vmlinux.patched Link: http://lkml.kernel.org/r/1392349908-29685-1-git-send-email-vnagarnaik@google.com Cc: Laurent Chavey <chavey@google.com> Cc: stable@vger.kernel.org # 3.10+ Signed-off-by: Vaibhav Nagarnaik <vnagarnaik@google.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2014-03-20trace, ring-buffer: Fix CPU hotplug callback registrationSrivatsa S. Bhat
Subsystems that want to register CPU hotplug callbacks, as well as perform initialization for the CPUs that are already online, often do it as shown below: get_online_cpus(); for_each_online_cpu(cpu) init_cpu(cpu); register_cpu_notifier(&foobar_cpu_notifier); put_online_cpus(); This is wrong, since it is prone to ABBA deadlocks involving the cpu_add_remove_lock and the cpu_hotplug.lock (when running concurrently with CPU hotplug operations). Instead, the correct and race-free way of performing the callback registration is: cpu_notifier_register_begin(); for_each_online_cpu(cpu) init_cpu(cpu); /* Note the use of the double underscored version of the API */ __register_cpu_notifier(&foobar_cpu_notifier); cpu_notifier_register_done(); Fix the tracing ring-buffer code by using thi