linux/kernel/trace, branch v3.4.43

tracing: Fix double free when function profile init failed

2013-04-17T04:27:26Z

commit 83e03b3fe4daffdebbb42151d5410d730ae50bd1 upstream. On the failure path, stat->start and stat->pages will refer same page. So it'll attempt to free the same page again and get kernel panic. Link: http://lkml.kernel.org/r/1364820385-32027-1-git-send-email-namhyung@kernel.org Signed-off-by: Namhyung Kim Cc: Frederic Weisbecker Cc: Namhyung Kim Signed-off-by: Steven Rostedt Signed-off-by: Greg Kroah-Hartman

ftrace: Consistently restore trace function on sysctl enabling

2013-04-12T16:38:45Z

commit 5000c418840b309251c5887f0b56503aae30f84c upstream. If we reenable ftrace via syctl, we currently set ftrace_trace_function based on the previous simplistic algorithm. This is inconsistent with what update_ftrace_function does. So better call that helper instead. Link: http://lkml.kernel.org/r/5151D26F.1070702@siemens.com Signed-off-by: Jan Kiszka Signed-off-by: Steven Rostedt Signed-off-by: Greg Kroah-Hartman

tracing: Prevent buffer overwrite disabled for latency tracers

2013-04-05T17:04:37Z

commit 613f04a0f51e6e68ac6fe571ab79da3c0a5eb4da upstream. The latency tracers require the buffers to be in overwrite mode, otherwise they get screwed up. Force the buffers to stay in overwrite mode when latency tracers are enabled. Added a flag_changed() method to the tracer structure to allow the tracers to see what flags are being changed, and also be able to prevent the change from happing. [Backported for 3.4-stable. Re-added current_trace NULL checks; removed allocated_snapshot field; adapted to tracing_trace_options_write without trace_set_options.] Signed-off-by: Steven Rostedt Signed-off-by: Lingzhu Xiang Reviewed-by: CAI Qian Signed-off-by: Greg Kroah-Hartman

tracing: Protect tracer flags with trace_types_lock

2013-04-05T17:04:37Z

commit 69d34da2984c95b33ea21518227e1f9470f11d95 upstream. Seems that the tracer flags have never been protected from synchronous writes. Luckily, admins don't usually modify the tracing flags via two different tasks. But if scripts were to be used to modify them, then they could get corrupted. Move the trace_types_lock that protects against tracers changing to also protect the flags being set. [Backported for 3.4, 3.0-stable. Moved return to after unlock.] Signed-off-by: Steven Rostedt Signed-off-by: Lingzhu Xiang Reviewed-by: CAI Qian Signed-off-by: Greg Kroah-Hartman

tracing: Fix free of probe entry by calling call_rcu_sched()

2013-03-28T19:12:06Z

commit 740466bc89ad8bd5afcc8de220f715f62b21e365 upstream. Because function tracing is very invasive, and can even trace calls to rcu_read_lock(), RCU access in function tracing is done with preempt_disable_notrace(). This requires a synchronize_sched() for updates and not a synchronize_rcu(). Function probes (traceon, traceoff, etc) must be freed after a synchronize_sched() after its entry has been removed from the hash. But call_rcu() is used. Fix this by using call_rcu_sched(). Also fix the usage to use hlist_del_rcu() instead of hlist_del(). Signed-off-by: Steven Rostedt Cc: Paul McKenney Signed-off-by: Greg Kroah-Hartman

tracing: Fix race in snapshot swapping

2013-03-28T19:12:06Z

commit 2721e72dd10f71a3ba90f59781becf02638aa0d9 upstream. Although the swap is wrapped with a spin_lock, the assignment of the temp buffer used to swap is not within that lock. It needs to be moved into that lock, otherwise two swaps happening on two different CPUs, can end up using the wrong temp buffer to assign in the swap. Luckily, all current callers of the swap function appear to have their own locks. But in case something is added that allows two different callers to call the swap, then there's a chance that this race can trigger and corrupt the buffers. New code is coming soon that will allow for this race to trigger. I've Cc'd stable, so this bug will not show up if someone backports one of the changes that can trigger this bug. Signed-off-by: Steven Rostedt Signed-off-by: Greg Kroah-Hartman

ftrace: Update the kconfig for DYNAMIC_FTRACE

2013-03-14T18:29:51Z

commit db05021d49a994ee40a9735d9c3cb0060c9babb8 upstream. The prompt to enable DYNAMIC_FTRACE (the ability to nop and enable function tracing at run time) had a confusing statement: "enable/disable ftrace tracepoints dynamically" This was written before tracepoints were added to the kernel, but now that tracepoints have been added, this is very confusing and has confused people enough to give wrong information during presentations. Not only that, I looked at the help text, and it still references that dreaded daemon that use to wake up once a second to update the nop locations and brick NICs, that hasn't been around for over five years. Time to bring the text up to the current decade. Reported-by: Ezequiel Garcia Signed-off-by: Steven Rostedt Signed-off-by: Greg Kroah-Hartman

ftrace: Call ftrace cleanup module notifier after all other notifiers

2013-03-03T22:06:38Z

commit 8c189ea64eea01ca20d102ddb74d6936dd16c579 upstream. Commit: c1bf08ac "ftrace: Be first to run code modification on modules" changed ftrace module notifier's priority to INT_MAX in order to process the ftrace nops before anything else could touch them (namely kprobes). This was the correct thing to do. Unfortunately, the ftrace module notifier also contains the ftrace clean up code. As opposed to the set up code, this code should be run *after* all the module notifiers have run in case a module is doing correct clean-up and unregisters its ftrace hooks. Basically, ftrace needs to do clean up on module removal, as it needs to know about code being removed so that it doesn't try to modify that code. But after it removes the module from its records, if a ftrace user tries to remove a probe, that removal will fail due as the record of that code segment no longer exists. Nothing really bad happens if the probe removal is called after ftrace did the clean up, but the ftrace removal function will return an error. Correct code (such as kprobes) will produce a WARN_ON() if it fails to remove the probe. As people get annoyed by frivolous warnings, it's best to do the ftrace clean up after everything else. By splitting the ftrace_module_notifier into two notifiers, one that does the module load setup that is run at high priority, and the other that is called for module clean up that is run at low priority, the problem is solved. Reported-by: Frank Ch. Eigler Acked-by: Masami Hiramatsu Signed-off-by: Steven Rostedt Signed-off-by: Greg Kroah-Hartman

ftrace: Be first to run code modification on modules

2013-01-28T04:47:42Z

commit c1bf08ac26e92122faab9f6c32ea8aba94612dae upstream. If some other kernel subsystem has a module notifier, and adds a kprobe to a ftrace mcount point (now that kprobes work on ftrace points), when the ftrace notifier runs it will fail and disable ftrace, as well as kprobes that are attached to ftrace points. Here's the error: WARNING: at kernel/trace/ftrace.c:1618 ftrace_bug+0x239/0x280() Hardware name: Bochs Modules linked in: fat(+) stap_56d28a51b3fe546293ca0700b10bcb29__8059(F) nfsv4 auth_rpcgss nfs dns_resolver fscache xt_nat iptable_nat nf_conntrack_ipv4 nf_defrag_ipv4 nf_nat_ipv4 nf_nat nf_conntrack lockd sunrpc ppdev parport_pc parport microcode virtio_net i2c_piix4 drm_kms_helper ttm drm i2c_core [last unloaded: bid_shared] Pid: 8068, comm: modprobe Tainted: GF 3.7.0-0.rc8.git0.1.fc19.x86_64 #1 Call Trace: [] warn_slowpath_common+0x7f/0xc0 [] ? __probe_kernel_read+0x46/0x70 [] ? 0xffffffffa017ffff [] ? 0xffffffffa017ffff [] warn_slowpath_null+0x1a/0x20 [] ftrace_bug+0x239/0x280 [] ftrace_process_locs+0x376/0x520 [] ftrace_module_notify+0x47/0x50 [] notifier_call_chain+0x4d/0x70 [] __blocking_notifier_call_chain+0x58/0x80 [] blocking_notifier_call_chain+0x16/0x20 [] sys_init_module+0x73/0x220 [] system_call_fastpath+0x16/0x1b ---[ end trace 9ef46351e53bbf80 ]--- ftrace failed to modify [] init_once+0x0/0x20 [fat] actual: cc:bb:d2:4b:e1 A kprobe was added to the init_once() function in the fat module on load. But this happened before ftrace could have touched the code. As ftrace didn't run yet, the kprobe system had no idea it was a ftrace point and simply added a breakpoint to the code (0xcc in the cc:bb:d2:4b:e1). Then when ftrace went to modify the location from a call to mcount/fentry into a nop, it didn't see a call op, but instead it saw the breakpoint op and not knowing what to do with it, ftrace shut itself down. The solution is to simply give the ftrace module notifier the max priority. This should have been done regardless, as the core code ftrace modification also happens very early on in boot up. This makes the module modification closer to core modification. Link: http://lkml.kernel.org/r/20130107140333.593683061@goodmis.org Acked-by: Masami Hiramatsu Reported-by: Frank Ch. Eigler Signed-off-by: Steven Rostedt

ring-buffer: Fix race between integrity check and readers

2013-01-17T16:50:51Z

commit 9366c1ba13fbc41bdb57702e75ca4382f209c82f upstream. The function rb_check_pages() was added to make sure the ring buffer's pages were sane. This check is done when the ring buffer size is modified as well as when the iterator is released (closing the "trace" file), as that was considered a non fast path and a good place to do a sanity check. The problem is that the check does not have any locks around it. If one process were to read the trace file, and another were to read the raw binary file, the check could happen while the reader is reading the file. The issues with this is that the check requires to clear the HEAD page before doing the full check and it restores it afterward. But readers require the HEAD page to exist before it can read the buffer, otherwise it gives a nasty warning and disables the buffer. By adding the reader lock around the check, this keeps the race from happening. Signed-off-by: Steven Rostedt Signed-off-by: Greg Kroah-Hartman