Messages in this thread Patch in this message |  | | Date | Wed, 6 Feb 2013 14:11:40 -0800 | From | tip-bot for Jiri Olsa <> | Subject | [tip:perf/core] perf perl scripts: Fix SIGALRM and pipe read race for rwtop |
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Commit-ID: b22e79395c0fe4c86dd35745a929366034386ccc Gitweb: http://git.kernel.org/tip/b22e79395c0fe4c86dd35745a929366034386ccc Author: Jiri Olsa <jolsa@redhat.com> AuthorDate: Tue, 5 Feb 2013 17:05:50 +0100 Committer: Arnaldo Carvalho de Melo <acme@redhat.com> CommitDate: Wed, 6 Feb 2013 18:09:27 -0300
perf perl scripts: Fix SIGALRM and pipe read race for rwtop
Fixing rwtop script race. The issue is caused by rwtop script triggering SIGALRM and underneath pipe reading layer reporting error when interrupted.
Fixing this by setting SA_RESTART for rwtop SIGALRM handler, which avoids interruption of the pipe reading layer.
The discussion for this issue & fix is here: https://lkml.org/lkml/2012/9/18/123
Signed-off-by: Jiri Olsa <jolsa@redhat.com> Original-patch-by: Andrew Jones <drjones@redhat.com> Cc: Andrew Jones <drjones@redhat.com> Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com> Cc: David Ahern <dsahern@gmail.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Ingo Molnar <mingo@elte.hu> 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/1360080351-3246-2-git-send-email-jolsa@redhat.com Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com> --- tools/perf/scripts/perl/rwtop.pl | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/tools/perf/scripts/perl/rwtop.pl b/tools/perf/scripts/perl/rwtop.pl index 4bb3ecd..8b20787 100644 --- a/tools/perf/scripts/perl/rwtop.pl +++ b/tools/perf/scripts/perl/rwtop.pl @@ -17,6 +17,7 @@ use lib "$ENV{'PERF_EXEC_PATH'}/scripts/perl/Perf-Trace-Util/lib"; use lib "./Perf-Trace-Util/lib"; use Perf::Trace::Core; use Perf::Trace::Util; +use POSIX qw/SIGALRM SA_RESTART/; my $default_interval = 3; my $nlines = 20; @@ -90,7 +91,10 @@ sub syscalls::sys_enter_write sub trace_begin { - $SIG{ALRM} = \&set_print_pending; + my $sa = POSIX::SigAction->new(\&set_print_pending); + $sa->flags(SA_RESTART); + $sa->safe(1); + POSIX::sigaction(SIGALRM, $sa) or die "Can't set SIGALRM handler: $!\n"; alarm 1; }
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