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perf: Use read() instead of lseek() in trace_event_read.c:skip()

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This is a small fix for a problem affecting live-mode, introduced
recently:

root@tropicana:~# perf trace rwtop
perf trace started with Perl
script /root/libexec/perf-core/scripts/perl/rwtop.pl

  Fatal: did not read header event

commit d00a47cce5 added a skip()
function to skip over e.g. header_page, but this doesn't work for
live mode.  This patch re-implements skip() to use read() instead of
lseek() to fix that.

Signed-off-by: Tom Zanussi <tzanussi@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Paul Mackerras <paulus@samba.org>
LKML-Reference: <1273032130.6383.28.camel@tropicana>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
This commit is contained in:
Tom Zanussi 2010-05-04 23:02:10 -05:00 committed by Frederic Weisbecker
parent 537b60d178
commit cbb5cf7ff6
1 changed files with 13 additions and 6 deletions
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19
tools/perf/util/trace-event-read.c
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@ -53,12 +53,6 @@ static unsigned long page_size;
static ssize_t calc_data_size;
static bool repipe;
/* If it fails, the next read will report it */
static void skip(int size)
{
lseek(input_fd, size, SEEK_CUR);
}
static int do_read(int fd, void *buf, int size)
{
int rsize = size;
@ -98,6 +92,19 @@ static int read_or_die(void *data, int size)
return r;
}
/* If it fails, the next read will report it */
static void skip(int size)
{
char buf[BUFSIZ];
int r;
while (size) {
r = size > BUFSIZ ? BUFSIZ : size;
read_or_die(buf, r);
size -= r;
};
}
static unsigned int read4(void)
{
unsigned int data;