perf: Fix exit() vs PERF_FORMAT_GROUP
authorPeter Zijlstra <peterz@infradead.org>
Tue, 11 May 2010 09:51:53 +0000 (11:51 +0200)
committerIngo Molnar <mingo@elte.hu>
Tue, 11 May 2010 13:46:43 +0000 (15:46 +0200)
commit050735b08ca8a016bbace4445fa025b88fee770b
tree68ce73ebb40dfcb66c9c18db9d31bfdb82c2e795
parente3174cfd2a1e28fff774681f00a0eef3d31da970
perf: Fix exit() vs PERF_FORMAT_GROUP

Both Stephane and Corey reported that PERF_FORMAT_GROUP didn't
work as expected if the task the counters were attached to quit
before the read() call.

The cause is that we unconditionally destroy the grouping when
we remove counters from their context. Fix this by splitting off
the group destroy from the list removal such that
perf_event_remove_from_context() does not do this and change
perf_event_release() to do so.

Reported-by: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Reported-by: Stephane Eranian <eranian@google.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: <stable@kernel.org> # .34.x
LKML-Reference: <1273571513.5605.3527.camel@twins>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
kernel/perf_event.c