On Thu, Nov 28, 2013 at 08:19:51AM -0700, David Ahern wrote:
> On 11/28/13, 3:30 AM, Jiri Olsa wrote:
> >@@ -151,21 +152,26 @@ unsigned long convert_unit(unsigned long value, char
> >*unit)
> > return value;
> > }
> >
> >+/*
> >+ * Read exactly 'n' bytes or return an error.
> >+ */
> > ssize_t readn(int fd, void *buf, size_t n)
> > {
> > void *buf_start = buf;
> >+ size_t left = n;
> >
> >- while (n) {
> >- ssize_t ret = read(fd, buf, n);
> >+ while (left) {
> >+ ssize_t ret = read(fd, buf, left);
> >
> > if (ret <= 0)
> > return ret;
>
> handle EINTR errors? no need to fail readn if the system call is
> interrupted.
right, how about the v3 below?
thanks,
jirka
---
Added a 'left' variable to make the flow clearer, and added a debug
check for the return value - returning 'n' is more obvious. Also do
not fail on EINTR error.
Added small comment for readn.
Original-patch-by: Ingo Molnar <[email protected]>
Signed-off-by: Jiri Olsa <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Frederic Weisbecker <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Namhyung Kim <[email protected]>
Cc: Mike Galbraith <[email protected]>
Cc: David Ahern <[email protected]>
Cc: Adrian Hunter <[email protected]>
Cc: Arnaldo Carvalho de Melo <[email protected]>
---
tools/perf/util/util.c | 19 +++++++++++++------
1 file changed, 13 insertions(+), 6 deletions(-)
diff --git a/tools/perf/util/util.c b/tools/perf/util/util.c
index 9440481..f12eada 100644
--- a/tools/perf/util/util.c
+++ b/tools/perf/util/util.c
@@ -6,6 +6,8 @@
#endif
#include <stdio.h>
#include <stdlib.h>
+#include <linux/kernel.h>
+#include <errno.h>
/*
* XXX We need to find a better place for these things...
@@ -151,21 +153,26 @@ unsigned long convert_unit(unsigned long value, char
*unit)
return value;
}
+/*
+ * Read exactly 'n' bytes or return an error.
+ */
ssize_t readn(int fd, void *buf, size_t n)
{
void *buf_start = buf;
+ size_t left = n;
- while (n) {
- ssize_t ret = read(fd, buf, n);
+ while (left) {
+ ssize_t ret = read(fd, buf, left);
- if (ret <= 0)
+ if ((ret <= 0) && (errno != EINTR))
return ret;
- n -= ret;
- buf += ret;
+ left -= ret;
+ buf += ret;
}
- return buf - buf_start;
+ BUG_ON((size_t)(buf - buf_start) != n);
+ return n;
}
size_t hex_width(u64 v)
--
1.8.3.1
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