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perf perl scripts: Fix SIGALRM and pipe read race for rwtop

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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>
This commit is contained in:
Jiri Olsa 2013-02-05 17:05:50 +01:00 • committed by Arnaldo Carvalho de Melo
commit b22e79395c
1 changed files with 5 additions and 1 deletions
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6
tools/perf/scripts/perl/rwtop.pl
View file

@ -17,6 +17,7 @@ use lib "$ENV{'PERF_EXEC_PATH'}/scripts/perl/Perf-Trace-Util/lib";
use lib "./Perf-Trace-Util/lib"; use lib "./Perf-Trace-Util/lib";
use Perf::Trace::Core; use Perf::Trace::Core;
use Perf::Trace::Util; use Perf::Trace::Util;
use POSIX qw/SIGALRM SA_RESTART/;
my $default_interval = 3; my $default_interval = 3;
my $nlines = 20; my $nlines = 20;
@ -90,7 +91,10 @@ sub syscalls::sys_enter_write
sub trace_begin 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; alarm 1;
} }