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2009-09-12tracing: show details of structures within the ftrace structuresSteven Rostedt
Some of the internal ftrace structures use structures within. The output of a field saying it is just a structure is useless for a format file. A binary reader of the ring buffer needs to know more about how the fields are broken up. This patch adds to the ftrace structure macros new fields to describe the structures inside a structure. Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2009-09-12tracing: use macros to create internal ftrace entry ring buffer structuresSteven Rostedt
The entries used by ftrace internal code (plugins) currently have their formats manually exported to userspace. That is, the format files in debugfs/tracing/events/ftrace/*/format are currently created by hand. This is a maintenance nightmare, and can easily become out of sync with what is actually shown. This patch uses the methodology of the TRACE_EVENT macros to build the structures so that their formats can be automated and this will keep the structures in sync with what users can see. This patch only changes the way the structures are created. Further patches will build off of this to automate the format files. Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2009-09-12tracing: allow filter predicates to handle ksym symbolsSteven Rostedt
This patch increases the max string used by predicates to handle KSYM_SYMBOL_LEN. Also moves an include to look nicer. Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2009-09-12tracing/filters: add filter DocumentationTom Zanussi
Documentation for event filters and formats. v2 changes: fix a few problems noticed by Randy Dunlap. Reviewed-by: Li Zefan <lizf@cn.fujitsu.com> Acked-by: Randy Dunlap <randy.dunlap@oracle.com> Signed-off-by: Tom Zanussi <tzanussi@gmail.com> LKML-Reference: <1252642431.8016.9.camel@tropicana> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2009-09-12tracing/profile: fix profile_disable vs module_unloadLi Zefan
If the correspoding module is unloaded before ftrace_profile_disable() is called, event->profile_disable() won't be called, which can cause oops: # insmod trace-events-sample.ko # perf record -f -a -e sample:foo_bar sleep 3 & # sleep 1 # rmmod trace_events_sample # insmod trace-events-sample.ko OOPS! Signed-off-by: Li Zefan <lizf@cn.fujitsu.com> LKML-Reference: <4A9214E3.2070807@cn.fujitsu.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2009-09-12tracing/function-graph: x86_64 stack allocation cleanupJiri Olsa
Only 24 bytes needs to be reserved on the stack for the function graph tracer on x86_64. Signed-off-by: Jiri Olsa <jolsa@redhat.com> LKML-Reference: <20090729085837.GB4998@jolsa.lab.eng.brq.redhat.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2009-09-12ftrace: __start_mcount_loc should be .init.rodataJohn Reiser
__start_mcount_loc[] is unused after init, yet occupies RAM forever as part of .rodata. 152kiB is typical on a 64-bit architecture. Instead, __start_mcount_loc should be in the interval [__init_begin, __init_end) so that the space is reclaimed after init. __start_mcount_loc[] is generated during the load portion of kernel build, and is used only by ftrace_init(). ftrace_init is declared '__init' and is in .init.text, which is freed after init. __start_mcount_loc is placed into .rodata by a call to MCOUNT_REC inside the RO_DATA macro of include/asm-generic/vmlinux.lds.h. The array *is* read-only, but more importantly it is not used after init. So the call to MCOUNT_REC should be moved from RO_DATA to INIT_DATA. This patch has been tested on x86_64 with CONFIG_DEBUG_PAGEALLOC=y which verifies that the address range never is accessed after init. Signed-off-by: John Reiser <jreiser@BitWagon.com> LKML-Reference: <4A6DF0B6.7080402@bitwagon.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2009-09-12tracing: do not update tracing_max_latency when tracer is stoppedCarsten Emde
The state of the function pair tracing_stop()/tracing_start() is correctly considered when tracer data are updated. However, the global and externally accessible variable tracing_max_latency is always updated - even when tracing is stopped. The update should only occur, if tracing was not stopped. Signed-off-by: Carsten Emde <C.Emde@osadl.org> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2009-09-12tracing: remove unused local variables in tracer probe functionsCarsten Emde
When the nsecs_to_usecs() conversion in probe_wakeup_sched_switch() and check_critical_timing() was moved to a later stage in order to avoid unnecessary computing, it was overlooked to remove the original variables, assignments and comments.. Signed-off-by: Carsten Emde <C.Emde@osadl.org> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2009-09-12tracing: prevent NULL pointer dereference in ftrace_raw_event_block_bio_bounceCarsten Emde
Booting 2.6.31 and executing echo 1 >/sys/kernel/debug/tracing/events/enable leads to BUG: unable to handle kernel NULL pointer dereference at (null) IP: [<c032a583>] ftrace_raw_event_block_bio_bounce+0x4b/0xb9 Apparently, bio = bio_map_user(q, NULL, uaddr, len, reading, gfp_mask); is called in block/blk-map.c:58 where bio->bi_bdev in set to NULL and still is NULL when an attempt is made to evaluate bio->bi_bdev->bd_dev in include/trace/events/block.h:189. The tracepoint should ensure bio->bi_bdev is not dereferenced, if NULL. Signed-off-by: Carsten Emde <C.Emde@osadl.org> LKML-Reference: <4AAAC9B1.9060505@osadl.org> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2009-09-11tracing: trace parser support for function and graphjolsa@redhat.com
Convert the writing to 'set_graph_function', 'set_ftrace_filter' and 'set_ftrace_notrace' to use the generic trace_parser 'trace_get_user' function. Removed FTRACE_ITER_CONT flag, since it's not needed after this change. Minor fix in set_graph_function display - g_show function. Signed-off-by: Jiri Olsa <jolsa@redhat.com> LKML-Reference: <1252682969-3366-4-git-send-email-jolsa@redhat.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2009-09-11tracing: trace parser support for set_eventjolsa@redhat.com
Convert the parsing of the file 'set_event' to use the generic trace_praser 'trace_get_user' function. Signed-off-by: Jiri Olsa <jolsa@redhat.com> LKML-Reference: <1252682969-3366-3-git-send-email-jolsa@redhat.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2009-09-11tracing: create generic trace parserjolsa@redhat.com
Create a "trace_parser" that can parse the user space input for separate words. struct trace_parser is the descriptor. Generic "trace_get_user" function that can be a helper to read multiple words passed in by user space. Signed-off-by: Jiri Olsa <jolsa@redhat.com> LKML-Reference: <1252682969-3366-2-git-send-email-jolsa@redhat.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2009-09-11tracing: consolidate code between trace_output.c and trace_function_graph.cSteven Rostedt
Both trace_output.c and trace_function_graph.c do basically the same thing to handle the printing of the latency-format. This patch moves the code into one function that both can use. Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2009-09-11tracing: add lock depth to entriesSteven Rostedt
This patch adds the lock depth of the big kernel lock to the generic entry header. This way we can see the depth of the lock and help in removing the BKL. Example: # _------=> CPU# # / _-----=> irqs-off # | / _----=> need-resched # || / _---=> hardirq/softirq # ||| / _--=> preempt-depth # |||| /_--=> lock-depth # |||||/ delay # cmd pid |||||| time | caller # \ / |||||| \ | / <idle>-0 2.N..3 5902255250us+: lock_acquire: read rcu_read_lock <idle>-0 2.N..3 5902255253us+: lock_release: rcu_read_lock <idle>-0 2dN..3 5902255257us+: lock_acquire: xtime_lock <idle>-0 2dN..4 5902255259us : lock_acquire: clocksource_lock <idle>-0 2dN..4 5902255261us+: lock_release: clocksource_lock Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2009-09-11tracing: move tgid out of generic entry and into userstackSteven Rostedt
The userstack trace required the recording of the tgid entry. Unfortunately, it was added to the generic entry where it wasted 4 bytes of every entry and was only used by one entry. This patch moves it out of the generic field and moves it into the only user (userstack_entry). Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2009-09-11tracing: add latency format to function_graph tracerSteven Rostedt
While debugging something with the function_graph tracer, I found the need to see the preempt count of the traces. Unfortunately, since the function graph tracer has its own output formatting, it does not honor the latency-format option. This patch makes the function_graph tracer honor the latency-format option, but still keeps control of the output. But now we have the same details that the latency-format supplies. # tracer: function_graph # # _-----=> irqs-off # / _----=> need-resched # | / _---=> hardirq/softirq # || / _--=> preempt-depth # ||| / # |||| # CPU|||| DURATION FUNCTION CALLS # | |||| | | | | | | 3) d..1 1.333 us | idle_cpu(); 3) d.h1 | tick_check_idle() { 3) d.h1 0.550 us | tick_check_oneshot_broadcast(); 3) d.h1 | tick_nohz_stop_idle() { 3) d.h1 | ktime_get() { 3) d.h1 | ktime_get_ts() { Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2009-09-10x86/tracing: comment need for atomic nopSteven Rostedt
The dynamic function tracer relys on the macro P6_NOP5 always being an atomic NOP. If for some reason it is changed to be two operations (like a nop2 nop3) it can faults within the kernel when the function tracer modifies the code. This patch adds a comment to note that the P6_NOPs are expected to be atomic. This will hopefully prevent anyone from changing that. Reported-by: Mathieu Desnoyer <mathieu.desnoyers@polymtl.ca> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2009-09-09tracing: move PRED macros to trace_events_filter.cLi Zefan
Move DEFINE_COMPARISON_PRED() and DEFINE_EQUALITY_PRED() to kernel/trace/trace_events_filter.c Signed-off-by: Li Zefan <lizf@cn.fujitsu.com> LKML-Reference: <4AA8579B.4020706@cn.fujitsu.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2009-09-09tracing: remove stats from struct tracerLi Zefan
Remove unused field @stats from struct tracer. Signed-off-by: Li Zefan <lizf@cn.fujitsu.com> LKML-Reference: <4AA8579B.4020706@cn.fujitsu.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2009-09-09tracing: format clean upsLi Zefan
Fix white-space formatting. Signed-off-by: Li Zefan <lizf@cn.fujitsu.com> LKML-Reference: <4AA8579B.4020706@cn.fujitsu.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2009-09-09tracing: remove dead codeLi Zefan
Removes unreachable code. Signed-off-by: Li Zefan <lizf@cn.fujitsu.com> LKML-Reference: <4AA8579B.4020706@cn.fujitsu.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2009-09-09tracing: do not grab lock in wakeup latency function tracingSteven Rostedt
The wakeup tracer, when enabled, has its own function tracer. It only traces the functions on the CPU where the task it is following is on. If a task is woken on one CPU but then migrates to another CPU before it wakes up, the latency tracer will then start tracing functions on the other CPU. To find which CPU the task is on, the wakeup function tracer performs a task_cpu(wakeup_task). But to make sure the task does not disappear it grabs the wakeup_lock, which is also taken when the task wakes up. By taking this lock, the function tracer does not need to worry about the task being freed as it checks its cpu. Jan Blunck found a problem with this approach on his 32 CPU box. When a task is being traced by the wakeup tracer, all functions take this lock. That means that on all 32 CPUs, each function call is taking this one lock to see if the task is on that CPU. This lock has just serialized all functions on all 32 CPUs. Needless to say, this caused major issues on that box. It would even lockup. This patch changes the wakeup latency to insert a probe on the migrate task tracepoint. When a task changes its CPU that it will run on, the probe will take note. Now the wakeup function tracer no longer needs to take the lock. It only compares the current CPU with a variable that holds the current CPU the task is on. We don't worry about races since it is OK to add or miss a function trace. Reported-by: Jan Blunck <jblunck@suse.de> Tested-by: Jan Blunck <jblunck@suse.de> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2009-09-09ring-buffer: consolidate interface of rb_buffer_peek()Robert Richter
rb_buffer_peek() operates with struct ring_buffer_per_cpu *cpu_buffer only. Thus, instead of passing variables buffer and cpu it is better to use cpu_buffer directly. This also reduces the risk of races since cpu_buffer is not calculated twice. Signed-off-by: Robert Richter <robert.richter@amd.com> LKML-Reference: <1249045084-3028-1-git-send-email-robert.richter@amd.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2009-09-06Merge branch 'tracing/core' of ↵Ingo Molnar
git://git.kernel.org/pub/scm/linux/kernel/git/frederic/random-tracing into tracing/core
2009-09-06Merge commit 'v2.6.31-rc9' into tracing/coreIngo Molnar
Merge reason: move from -rc5 to -rc9. Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-09-05Linux 2.6.31-rc9Linus Torvalds
2009-09-05Merge branch 'for-linus' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/ieee1394/linux1394-2.6 * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ieee1394/linux1394-2.6: firewire: sbp2: fix freeing of unallocated memory firewire: ohci: fix Ricoh R5C832, video reception firewire: ohci: fix Agere FW643 and multiple cameras firewire: core: fix crash in iso resource management
2009-09-05powerpc: Fix i8259 interrupt driver kernel crash on ML510Roderick Colenbrander
This patch fixes a null pointer exception caused by removal of 'ack()' for level interrupts in the Xilinx interrupt driver. A recent change to the xilinx interrupt controller removed the ack hook for level irqs. Signed-off-by: Roderick Colenbrander <thunderbird2k@gmail.com> Signed-off-by: Grant Likely <grant.likely@secretlab.ca> Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-09-05Merge git://git.infradead.org/~dwmw2/mtd-2.6.31Linus Torvalds
* git://git.infradead.org/~dwmw2/mtd-2.6.31: JFFS2: add missing verify buffer allocation/deallocation mtd: nftl: fix offset alignments mtd: nftl: write support is broken mtd: m25p80: fix null pointer dereference bug
2009-09-05Merge branch 'for-linus' of git://git.kernel.dk/linux-2.6-blockLinus Torvalds
* 'for-linus' of git://git.kernel.dk/linux-2.6-block: block: Allow changing max_sectors_kb above the default 512
2009-09-05Merge branch 'fix/oxygen' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound-2.6 * 'fix/oxygen' of git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound-2.6: sound: oxygen: handle cards with missing EEPROM sound: oxygen: fix MCLK rate for 192 kHz playback
2009-09-05Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-2.6Linus Torvalds
* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-2.6: tc: Fix unitialized kernel memory leak pkt_sched: Revert tasklet_hrtimer changes. net: sk_free() should be allowed right after sk_alloc() gianfar: gfar_remove needs to call unregister_netdev() ipw2200: firmware DMA loading rework
2009-09-05Merge git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6Linus Torvalds
* git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6: crypto: skcipher - Fix skcipher_dequeue_givcrypt NULL test
2009-09-05Merge branch 'fixes' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/davej/cpufreq * 'fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/davej/cpufreq: [CPUFREQ] Re-enable cpufreq suspend and resume code
2009-09-05Merge branch 'release' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/aegl/linux-2.6 * 'release' of git://git.kernel.org/pub/scm/linux/kernel/git/aegl/linux-2.6: [IA64] fix csum_ipv6_magic() [IA64] Fix warning in dma-mapping.c
2009-09-05Merge branch 'for-linus' of git://oss.sgi.com/xfs/xfsLinus Torvalds
* 'for-linus' of git://oss.sgi.com/xfs/xfs: xfs: actually enable the swapext compat handler
2009-09-05Merge branch 'for-linus' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/ryusuke/nilfs2 * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ryusuke/nilfs2: nilfs2: fix preempt count underflow in nilfs_btnode_prepare_change_key
2009-09-05Merge branch 'for-linus' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu: percpu: don't assume existence of cpu0
2009-09-05Merge branch 'slab/urgent' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/penberg/slab-2.6 * 'slab/urgent' of git://git.kernel.org/pub/scm/linux/kernel/git/penberg/slab-2.6: slub: Fix kmem_cache_destroy() with SLAB_DESTROY_BY_RCU
2009-09-05Merge git://git.kernel.org/pub/scm/linux/kernel/git/agk/linux-2.6-dmLinus Torvalds
* git://git.kernel.org/pub/scm/linux/kernel/git/agk/linux-2.6-dm: dm snapshot: fix on disk chunk size validation dm exception store: split set_chunk_size dm snapshot: fix header corruption race on invalidation dm snapshot: refactor zero_disk_area to use chunk_io dm log: userspace add luid to distinguish between concurrent log instances dm raid1: do not allow log_failure variable to unset after being set dm log: remove incorrect field from userspace table output dm log: fix userspace status output dm stripe: expose correct io hints dm table: add more context to terse warning messages dm table: fix queue_limit checking device iterator dm snapshot: implement iterate devices dm multipath: fix oops when request based io fails when no paths
2009-09-05Merge branch 'for-linus' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/jbarnes/pci-2.6 * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jbarnes/pci-2.6: PCI SR-IOV: correct broken resource alignment calculations
2009-09-05Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/sparc-2.6Linus Torvalds
* git://git.kernel.org/pub/scm/linux/kernel/git/davem/sparc-2.6: sparc64: Fix bootup with mcount in some configs. sparc64: Kill spurious NMI watchdog triggers by increasing limit to 30 seconds.
2009-09-05Merge branch 'perfcounters-fixes-for-linus' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip * 'perfcounters-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: perf_counter/powerpc: Fix cache event codes for POWER7 perf_counter: Fix /0 bug in swcounters perf_counters: Increase paranoia level
2009-09-05Merge branch 'for-linus' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input: Input: atkbd - add Compaq Presario R4000-series repeat quirk Input: i8042 - add Acer Aspire 5536 to the nomux list
2009-09-05ext2: fix unbalanced kmap()/kunmap()Nicolas Pitre
In ext2_rename(), dir_page is acquired through ext2_dotdot(). It is then released through ext2_set_link() but only if old_dir != new_dir. Failing that, the pkmap reference count is never decremented and the page remains pinned forever. Repeat that a couple times with highmem pages and all pkmap slots get exhausted, and every further kmap() calls end up stalling on the pkmap_map_wait queue at which point the whole system comes to a halt. Signed-off-by: Nicolas Pitre <nico@marvell.com> Acked-by: Theodore Ts'o <tytso@mit.edu> Cc: stable@kernel.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-09-05Merge branch 'upstream-linus' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/jlbec/ocfs2 * 'upstream-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jlbec/ocfs2: ocfs2: ocfs2_write_begin_nolock() should handle len=0 ocfs2: invalidate dentry if its dentry_lock isn't initialized.
2009-09-05pty: don't limit the writes to 'pty_space()' inside 'pty_write()'Linus Torvalds
The whole write-room thing is something that is up to the _caller_ to worry about, not the pty layer itself. The total buffer space will still be limited by the buffering routines themselves, so there is no advantage or need in having pty_write() artificially limit the size somehow. And what happened was that the caller (the n_tty line discipline, in this case) may have verified that there is room for 2 bytes to be written (for NL -> CRNL expansion), and it used to then do those writes as two single-byte writes. And if the first byte written (CR) then caused a new tty buffer to be allocated, pty_space() may have returned zero when trying to write the second byte (LF), and then incorrectly failed the write - leading to a lost newline character. This should finally fix http://bugzilla.kernel.org/show_bug.cgi?id=14015 Reported-by: Mikael Pettersson <mikpe@it.uu.se> Acked-by: Alan Cox <alan@lxorguk.ukuu.org.uk> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-09-05n_tty: do O_ONLCR translation as a single writeLinus Torvalds
When translating CR to CRNL in the n_tty line discipline, we did it as two tty_put_char() calls. Which works, but is stupid, and has caused problems before too with bad interactions with the write_room() logic. The generic USB serial driver had that problem, for example. Now the pty layer had similar issues after being moved to the generic tty buffering code (in commit d945cb9cce20ac7143c2de8d88b187f62db99bdc: "pty: Rework the pty layer to use the normal buffering logic"). So stop doing the silly separate two writes, and do it as a single write instead. That's what the n_tty layer already does for the space expansion of tabs (XTABS), and it means that we'll now always have just a single write for the CRNL to match the single 'tty_write_room()' test, which hopefully means that the next time somebody screws up buffering, it won't cause weeks of debugging. Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-09-05exec: do not sleep in TASK_TRACED under ->cred_guard_mutexOleg Nesterov
Tom Horsley reports that his debugger hangs when it tries to read /proc/pid_of_tracee/maps, this happens since "mm_for_maps: take ->cred_guard_mutex to fix the race with exec" 04b836cbf19e885f8366bccb2e4b0474346c02d commit in 2.6.31. But the root of the problem lies in the fact that do_execve() path calls tracehook_report_exec() which can stop if the tracer sets PT_TRACE_EXEC. The tracee must not sleep in TASK_TRACED holding this mutex. Even if we remove ->cred_guard_mutex from mm_for_maps() and proc_pid_attr_write(), another task doing PTRACE_ATTACH should not hang until it is killed or the tracee resumes. With this patch do_execve() does not use ->cred_guard_mutex directly and we do not hold it throughout, instead: - introduce prepare_bprm_creds() helper, it locks the mutex and calls prepare_exec_creds() to initialize bprm->cred. - install_exec_creds() drops the mutex after commit_creds(), and thus before tracehook_report_exec()->ptrace_stop(). or, if exec fails, free_bprm() drops this mutex when bprm->cred != NULL which indicates install_exec_creds() was not called. Reported-by: Tom Horsley <tom.horsley@att.net> Signed-off-by: Oleg Nesterov <oleg@redhat.com> Acked-by: David Howells <dhowells@redhat.com> Cc: Roland McGrath <roland@redhat.com> Cc: James Morris <jmorris@namei.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>