linux/include, branch v3.2.56

jiffies: Avoid undefined behavior from signed overflow

2014-04-01T23:59:01Z

commit 5a581b367b5df0531265311fc681c2abd377e5e6 upstream. According to the C standard 3.4.3p3, overflow of a signed integer results in undefined behavior. This commit therefore changes the definitions of time_after(), time_after_eq(), time_after64(), and time_after_eq64() to avoid this undefined behavior. The trick is that the subtraction is done using unsigned arithmetic, which according to 6.2.5p9 cannot overflow because it is defined as modulo arithmetic. This has the added (though admittedly quite small) benefit of shortening four lines of code by four characters each. Note that the C standard considers the cast from unsigned to signed to be implementation-defined, see 6.3.1.3p3. However, on a two's-complement system, an implementation that defines anything other than a reinterpretation of the bits is free to come to me, and I will be happy to act as a witness for its being committed to an insane asylum. (Although I have nothing against saturating arithmetic or signals in some cases, these things really should not be the default when compiling an operating-system kernel.) Signed-off-by: Paul E. McKenney Cc: John Stultz Cc: "David S. Miller" Cc: Arnd Bergmann Cc: Ingo Molnar Cc: Linus Torvalds Cc: Eric Dumazet Cc: Kevin Easton [ paulmck: Included time_after64() and time_after_eq64(), as suggested by Eric Dumazet, also fixed commit message.] Reviewed-by: Josh Triplett Signed-off-by: Ben Hutchings

tracing: Do not add event files for modules that fail tracepoints

2014-04-01T23:58:57Z

commit 45ab2813d40d88fc575e753c38478de242d03f88 upstream. If a module fails to add its tracepoints due to module tainting, do not create the module event infrastructure in the debugfs directory. As the events will not work and worse yet, they will silently fail, making the user wonder why the events they enable do not display anything. Having a warning on module load and the events not visible to the users will make the cause of the problem much clearer. Link: http://lkml.kernel.org/r/20140227154923.265882695@goodmis.org Fixes: 6d723736e472 "tracing/events: add support for modules to TRACE_EVENT" Acked-by: Mathieu Desnoyers Cc: Rusty Russell Signed-off-by: Steven Rostedt Signed-off-by: Ben Hutchings

compiler/gcc4: Make quirk for asm_volatile_goto() unconditional

2014-04-01T23:58:51Z

commit a9f180345f5378ac87d80ed0bea55ba421d83859 upstream. I started noticing problems with KVM guest destruction on Linux 3.12+, where guest memory wasn't being cleaned up. I bisected it down to the commit introducing the new 'asm goto'-based atomics, and found this quirk was later applied to those. Unfortunately, even with GCC 4.8.2 (which ostensibly fixed the known 'asm goto' bug) I am still getting some kind of miscompilation. If I enable the asm_volatile_goto quirk for my compiler, KVM guests are destroyed correctly and the memory is cleaned up. So make the quirk unconditional for now, until bug is found and fixed. Suggested-by: Linus Torvalds Signed-off-by: Steven Noonan Cc: Peter Zijlstra Cc: Steven Rostedt Cc: Jakub Jelinek Cc: Richard Henderson Cc: Andrew Morton Cc: Oleg Nesterov Link: http://lkml.kernel.org/r/1392274867-15236-1-git-send-email-steven@uplinklabs.net Link: http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58670 Signed-off-by: Ingo Molnar Signed-off-by: Ben Hutchings

xen: install xen/gntdev.h and xen/gntalloc.h

2014-04-01T23:58:50Z

commit 564eb714f5f09ac733c26860d5f0831f213fbdf1 upstream. xen/gntdev.h and xen/gntalloc.h both provide userspace ABIs so they should be installed. Signed-off-by: David Vrabel Signed-off-by: Konrad Rzeszutek Wilk [bwh: Backported to 3.2: no renaming is required] Signed-off-by: Ben Hutchings

ore: Fix wrong math in allocation of per device BIO

2014-04-01T23:58:45Z

commit aad560b7f63b495f48a7232fd086c5913a676e6f upstream. At IO preparation we calculate the max pages at each device and allocate a BIO per device of that size. The calculation was wrong on some unaligned corner cases offset/length combination and would make prepare return with -ENOMEM. This would be bad for pnfs-objects that would in that case IO through MDS. And fatal for exofs were it would fail writes with EIO. Fix it by doing the proper math, that will work in all cases. (I ran a test with all possible offset/length combinations this time round). Also when reading we do not need to allocate for the parity units since we jump over them. Also lower the max_io_length to take into account the parity pages so not to allocate BIOs bigger than PAGE_SIZE Signed-off-by: Boaz Harrosh Signed-off-by: Ben Hutchings

fuse: fix pipe_buf_operations

2014-04-01T23:58:44Z

commit 28a625cbc2a14f17b83e47ef907b2658576a32aa upstream. Having this struct in module memory could Oops when if the module is unloaded while the buffer still persists in a pipe. Since sock_pipe_buf_ops is essentially the same as fuse_dev_pipe_buf_steal merge them into nosteal_pipe_buf_ops (this is the same as default_pipe_buf_ops except stealing the page from the buffer is not allowed). Reported-by: Al Viro Signed-off-by: Miklos Szeredi [bwh: Backported to 3.2: adjust context] Signed-off-by: Ben Hutchings

libata: disable LPM for some WD SATA-I devices

2014-04-01T23:58:43Z

commit ecd75ad514d73efc1bbcc5f10a13566c3ace5f53 upstream. For some reason, some early WD drives spin up and down drives erratically when the link is put into slumber mode which can reduce the life expectancy of the device significantly. Unfortunately, we don't have full list of devices and given the nature of the issue it'd be better to err on the side of false positives than the other way around. Let's disable LPM on all WD devices which match one of the known problematic model prefixes and are SATA-I. As horkage list doesn't support matching SATA capabilities, this is implemented as two horkages - WD_BROKEN_LPM and NOLPM. The former is set for the known prefixes and sets the latter if the matched device is SATA-I. Note that this isn't optimal as this disables all LPM operations and partial link power state reportedly works fine on these; however, the way LPM is implemented in libata makes it difficult to precisely map libata LPM setting to specific link power state. Well, these devices are already fairly outdated. Let's just disable whole LPM for now. Signed-off-by: Tejun Heo Reported-and-tested-by: Nikos Barkas Reported-and-tested-by: Ioannis Barkas References: https://bugzilla.kernel.org/show_bug.cgi?id=57211 [bwh: Backported to 3.2: - Adjust context - Use literal 76 instead of ATA_ID_SATA_CAPABILITY] Signed-off-by: Ben Hutchings

sched/rt: Avoid updating RT entry timeout twice within one tick period

2014-02-15T19:20:18Z

commit 57d2aa00dcec67afa52478730f2b524521af14fb upstream. The issue below was found in 2.6.34-rt rather than mainline rt kernel, but the issue still exists upstream as well. So please let me describe how it was noticed on 2.6.34-rt: On this version, each softirq has its own thread, it means there is at least one RT FIFO task per cpu. The priority of these tasks is set to 49 by default. If user launches an RT FIFO task with priority lower than 49 of softirq RT tasks, it's possible there are two RT FIFO tasks enqueued one cpu runqueue at one moment. By current strategy of balancing RT tasks, when it comes to RT tasks, we really need to put them off to a CPU that they can run on as soon as possible. Even if it means a bit of cache line flushing, we want RT tasks to be run with the least latency. When the user RT FIFO task which just launched before is running, the sched timer tick of the current cpu happens. In this tick period, the timeout value of the user RT task will be updated once. Subsequently, we try to wake up one softirq RT task on its local cpu. As the priority of current user RT task is lower than the softirq RT task, the current task will be preempted by the higher priority softirq RT task. Before preemption, we check to see if current can readily move to a different cpu. If so, we will reschedule to allow the RT push logic to try to move current somewhere else. Whenever the woken softirq RT task runs, it first tries to migrate the user FIFO RT task over to a cpu that is running a task of lesser priority. If migration is done, it will send a reschedule request to the found cpu by IPI interrupt. Once the target cpu responds the IPI interrupt, it will pick the migrated user RT task to preempt its current task. When the user RT task is running on the new cpu, the sched timer tick of the cpu fires. So it will tick the user RT task again. This also means the RT task timeout value will be updated again. As the migration may be done in one tick period, it means the user RT task timeout value will be updated twice within one tick. If we set a limit on the amount of cpu time for the user RT task by setrlimit(RLIMIT_RTTIME), the SIGXCPU signal should be posted upon reaching the soft limit. But exactly when the SIGXCPU signal should be sent depends on the RT task timeout value. In fact the timeout mechanism of sending the SIGXCPU signal assumes the RT task timeout is increased once every tick. However, currently the timeout value may be added twice per tick. So it results in the SIGXCPU signal being sent earlier than expected. To solve this issue, we prevent the timeout value from increasing twice within one tick time by remembering the jiffies value of last updating the timeout. As long as the RT task's jiffies is different with the global jiffies value, we allow its timeout to be updated. Signed-off-by: Ying Xue Signed-off-by: Fan Du Reviewed-by: Yong Zhang Acked-by: Steven Rostedt Cc: Link: http://lkml.kernel.org/r/1342508623-2887-1-git-send-email-ying.xue@windriver.com Signed-off-by: Ingo Molnar [ lizf: backported to 3.4: adjust context ] Signed-off-by: Li Zefan [bwh: Backported to 3.2: adjust filename] Signed-off-by: Ben Hutchings

mm: hugetlbfs: fix hugetlbfs optimization

2014-02-15T19:20:17Z

commit 27c73ae759774e63313c1fbfeb17ba076cea64c5 upstream. Commit 7cb2ef56e6a8 ("mm: fix aio performance regression for database caused by THP") can cause dereference of a dangling pointer if split_huge_page runs during PageHuge() if there are updates to the tail_page->private field. Also it is repeating compound_head twice for hugetlbfs and it is running compound_head+compound_trans_head for THP when a single one is needed in both cases. The new code within the PageSlab() check doesn't need to verify that the THP page size is never bigger than the smallest hugetlbfs page size, to avoid memory corruption. A longstanding theoretical race condition was found while fixing the above (see the change right after the skip_unlock label, that is relevant for the compound_lock path too). By re-establishing the _mapcount tail refcounting for all compound pages, this also fixes the below problem: echo 0 >/sys/kernel/mm/hugepages/hugepages-2048kB/nr_hugepages BUG: Bad page state in process bash pfn:59a01 page:ffffea000139b038 count:0 mapcount:10 mapping: (null) index:0x0 page flags: 0x1c00000000008000(tail) Modules linked in: CPU: 6 PID: 2018 Comm: bash Not tainted 3.12.0+ #25 Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011 Call Trace: dump_stack+0x55/0x76 bad_page+0xd5/0x130 free_pages_prepare+0x213/0x280 __free_pages+0x36/0x80 update_and_free_page+0xc1/0xd0 free_pool_huge_page+0xc2/0xe0 set_max_huge_pages.part.58+0x14c/0x220 nr_hugepages_store_common.isra.60+0xd0/0xf0 nr_hugepages_store+0x13/0x20 kobj_attr_store+0xf/0x20 sysfs_write_file+0x189/0x1e0 vfs_write+0xc5/0x1f0 SyS_write+0x55/0xb0 system_call_fastpath+0x16/0x1b Signed-off-by: Khalid Aziz Signed-off-by: Andrea Arcangeli Tested-by: Khalid Aziz Cc: Pravin Shelar Cc: Greg Kroah-Hartman Cc: Ben Hutchings Cc: Christoph Lameter Cc: Johannes Weiner Cc: Mel Gorman Cc: Rik van Riel Cc: Andi Kleen Cc: Minchan Kim Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds [Khalid Aziz: Backported to 3.4] Signed-off-by: Ben Hutchings

pci: Add PCI_DEVICE_SUB() macro

2014-02-15T19:20:16Z

This was added as part of commit 3d567e0e291c ('tg3: Set 10_100_ONLY flag for additional 10/100 Mbps devices') upstream and is needed by the following patch to ahci. Signed-off-by: Ben Hutchings