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author | Davidlohr Bueso <dave@stgolabs.net> | 2015-04-16 19:49:12 (GMT) |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2015-04-17 13:04:11 (GMT) |
commit | 11163348a23cdbcdca5fb42485418e75f8566a5c (patch) | |
tree | 591adeddbcc89b51e047223b60b45500764fcc89 /lib | |
parent | 15beb694c66146e1133b9ff81d54e3ef3daa1d7c (diff) | |
download | linux-11163348a23cdbcdca5fb42485418e75f8566a5c.tar.xz |
oprofile: reduce mmap_sem hold for mm->exe_file
sync_buffer() needs the mmap_sem for two distinct operations, both only
occurring upon user context switch handling:
1) Dealing with the exe_file.
2) Adding the dcookie data as we need to lookup the vma that
backs it. This is done via add_sample() and add_data().
This patch isolates 1), for it will no longer need the mmap_sem for
serialization. However, for now, make of the more standard
get_mm_exe_file(), requiring only holding the mmap_sem to read the value,
and relying on reference counting to make sure that the exe file won't
dissappear underneath us while doing the get dcookie.
As a consequence, for 2) we move the mmap_sem locking into where we really
need it, in lookup_dcookie(). The benefits are twofold: reduce mmap_sem
hold times, and cleaner code.
[akpm@linux-foundation.org: export get_mm_exe_file for arch/x86/oprofile/oprofile.ko]
Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Cc: Robert Richter <rric@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'lib')
0 files changed, 0 insertions, 0 deletions