Commit b22e7939 authored by Jiri Olsa's avatar Jiri Olsa Committed by Arnaldo Carvalho de Melo

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/2012/9/18/123Signed-off-by: default avatarJiri Olsa <jolsa@redhat.com>
Original-patch-by: default avatarAndrew 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.comSigned-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent 0c5268bf
...@@ -17,6 +17,7 @@ use lib "$ENV{'PERF_EXEC_PATH'}/scripts/perl/Perf-Trace-Util/lib"; ...@@ -17,6 +17,7 @@ use lib "$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 ...@@ -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;
} }
......
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