In addition to using refcounts for the struct thread lifetime
management, we need to protect access to machine->threads from
concurrent access.
That happens in 'perf top', where a thread processes events, inserting
and deleting entries from that rb_tree while another thread decays
hist_entries, that end up dropping references and ultimately deleting
threads from the rb_tree and releasing its resources when no further
hist_entry (or other data structures, like in 'perf sched') references
it.
So the rule is the same for refcounts + protected trees in the kernel,
get the tree lock, find object, bump the refcount, drop the tree lock,
return, use object, drop the refcount if no more use of it is needed,
keep it if storing it in some other data structure, drop when releasing
that data structure.
I.e. pair "t = machine__find(new)_thread()" with a "thread__put(t)", and
"perf_event__preprocess_sample(&al)" with "addr_location__put(&al)".
The addr_location__put() one is because as we return references to
several data structures, we may end up adding more reference counting
for the other data structures and then we'll drop it at
addr_location__put() time.
Acked-by: David Ahern <dsahern@gmail.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: Don Zickus <dzickus@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/n/tip-bs9rt4n0jw3hi9f3zxyy3xln@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
commit: f3b623b849 ("perf tools: Reference count struct thread")
appends every thread->node to dead_threads in machine__remove_thread()
and list_del_init() this node in thread__put().
perf_event__exit_del_thread() releases thread wihout using
machine__remove_thread(), and causes a NULL pointer crash when
list_del_init(&thread->node) is called. Fix this by using
machine_remove_thread() instead of using thread__put() directly.
This problem can be reproduced as following:
$ perf record ls
$ perf buildid-list --with-hits
[ 3874.195070] perf[1018]: segfault at 0 ip 00000000004b0b15 sp
00007ffc35b44780 error 6 in perf[400000+166000]
Segmentation fault
After this patch:
$ perf record ls
$ perf buildid-list --with-hits
bc23e7c3281e542650ba4324421d6acf78f4c23e /proc/kcore
643324cb0e969f30c56d660f167f84a150845511 [vdso]
0000000000000000000000000000000000000000 /bin/busybox
...
Signed-off-by: He Kuang <hekuang@huawei.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/r/1428658500-6483-1-git-send-email-hekuang@huawei.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
int build_id_cache__add_s(const char *sbuild_id, const char *debugdir,
const char *name, bool is_kallsyms, bool is_vdso)
{
...
if (access(filename, F_OK)) {
^--------------------------------------------------------- [1]
if (is_kallsyms) {
if (copyfile("/proc/kallsyms", filename))
goto out_free;
} else if (link(realname, filename) && copyfile(name, filename))
^-----------------------------^------------- [2]
\------------ [3]
goto out_free;
}
...
When multiple instances of perf record get to [1] at more or less same time and
run access() one or more may get failure because the file does not exist yet
(since the first instance did not have chance to link it yet).
At this point the race moves to link() at [2] where first thread to get
there links file and goes on but second one gets -EEXIST so it runs
copyfile [3] which truncates the file.
reproducer:
rm -rf /root/.debug
for cpu in $(awk '/processor/ {print $3}' /proc/cpuinfo); do
perf record -a -v -T -F 1000 -C $cpu \
-o perf-${cpu}.data sleep 5 2> /dev/null &
done
wait
and simply search for empty files by:
find /lib/modules/`uname -r`/kernel/* -size 0
Signed-off-by: Milos Vyletel <milos@redhat.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/r/1426847846-11112-1-git-send-email-milos@redhat.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Add --purge FILE to remove all caches of FILE.
Since the current --remove FILE removes a cache which has
same build-id of given FILE. Since the command takes a
FILE path, it can confuse user who tries to remove cache
about FILE path.
-----
# ./perf buildid-cache -v --add ./perf
Adding 133b7b5486d987a5ab5c3ebf4ea14941f45d4d4f ./perf: Ok
# (update the ./perf binary)
# ./perf buildid-cache -v --remove ./perf
Removing 305bbd1be68f66eca7e2d78db294653031edfa79 ./perf: FAIL
./perf wasn't in the cache
-----
Actually, the --remove's FAIL is not shown, it just silently fails.
So, this patch adds --purge FILE action for such usecase.
perf buildid-cache --purge FILE removes all caches which has same FILE
path.
In other words, it removes all caches including old binaries.
-----
# ./perf buildid-cache -v --add ./perf
Adding 133b7b5486d987a5ab5c3ebf4ea14941f45d4d4f ./perf: Ok
# (update the ./perf binary)
# ./perf buildid-cache -v --purge ./perf
Removing 133b7b5486d987a5ab5c3ebf4ea14941f45d4d4f ./perf: Ok
-----
BTW, if you want to purge all the caches, remove ~/.debug/* .
Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: Hemant Kumar <hemant@linux.vnet.ibm.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/20150227045026.1999.64084.stgit@localhost.localdomain
[ s/dirname/dir_name/g to fix build on fedora14, where dirname is a global ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Add new buildid cache if the update target file is not cached.
This can happen when an old binary is replaced by new one after caching
the old one. In this case, user sees his operation just failed.
But it does not look straight, since user just pass the binary "path",
not "build-id".
----
# ./perf buildid-cache --add ./perf
(update ./perf to new binary)
# ./perf buildid-cache --update ./perf
./perf wasn't in the cache
#
----
This patch adds given new binary to cache if the new binary is
not cached. So we'll not see the above error.
----
# ./perf buildid-cache --add ./perf
(update ./perf to new binary)
# ./perf buildid-cache --update ./perf
#
----
Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: Hemant Kumar <hemant@linux.vnet.ibm.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/20150226065440.23912.1494.stgit@localhost.localdomain
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
This patch adds support for the new PERF_RECORD_MMAP2 record type
exposed by the kernel. This is an extended PERF_RECORD_MMAP record.
It adds for each file-backed mapping the device major, minor number and
the inode number and generation.
This triplet uniquely identifies the source of a file-backed mapping. It
can be used to detect identical virtual mappings between processes, for
instance.
The patch will prefer MMAP2 over MMAP.
Signed-off-by: Stephane Eranian <eranian@google.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung.kim@lge.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1377079825-19057-3-git-send-email-eranian@google.com
[ Cope with 314add6 "Change machine__findnew_thread() to set thread pid",
fix 'perf test' regression test entry affected,
use perf_missing_features.mmap2 to fallback to not using .mmap2 in older kernels,
so that new tools can work with kernels where this feature is not present ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
When we were processing a PERF_RECORD_EXIT event we first used
machine__findnew_thread for both the thread exiting and for its parent,
only to use just the thread struct associated with the one exiting, and
to just delete it.
If it existed, i.e. not created at this very moment in
machine__findnew_thread, it will be moved to the machine->dead_threads
linked list, because we may have hist_entries pointing to it, but if it
was created just do be deleted, it will just sit there with no
references at all.
Use the new machine__find_thread() method so that if it is not there, we
don't create it.
As a bonus the parent thread will also not be created at this point.
Create process_fork() and process_exit() helpers to use this and make
the builtins use it instead of the generic process_task(), ditched by
this patch.
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Namhyung Kim <namhyung@gmail.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/n/tip-z7n2y98ebjyrvmytaope4vdl@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
perf defines both __used and __unused variables to use for marking
unused variables. The variable __used is defined to
__attribute__((__unused__)), which contradicts the kernel definition to
__attribute__((__used__)) for new gcc versions. On Android, __used is
also defined in system headers and this leads to warnings like: warning:
'__used__' attribute ignored
__unused is not defined in the kernel and is not a standard definition.
If __unused is included everywhere instead of __used, this leads to
conflicts with glibc headers, since glibc has a variables with this name
in its headers.
The best approach is to use __maybe_unused, the definition used in the
kernel for __attribute__((unused)). In this way there is only one
definition in perf sources (instead of 2 definitions that point to the
same thing: __used and __unused) and it works on both Linux and Android.
This patch simply replaces all instances of __used and __unused with
__maybe_unused.
Signed-off-by: Irina Tirdea <irina.tirdea@intel.com>
Acked-by: Pekka Enberg <penberg@kernel.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Namhyung Kim <namhyung.kim@lge.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/r/1347315303-29906-7-git-send-email-irina.tirdea@intel.com
[ committer note: fixed up conflict with a116e05 in builtin-sched.c ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Arnaldo Carvalho de Melo
He Kuang
Milos Vyletel
Masami Hiramatsu
Jiri Olsa
Namhyung Kim
Stephane Eranian
Adrian Hunter
Jiri Olsa
Andrew Vagin
Irina Tirdea