Messages in this thread Patch in this message |  | | Date | Thu, 28 Nov 2013 16:43:50 +0100 | From | Jiri Olsa <> | Subject | [PATCHv3 3/7] perf tools: Fine tune readn function |
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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 <mingo@kernel.org> Signed-off-by: Jiri Olsa <jolsa@redhat.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Mike Galbraith <efault@gmx.de> Cc: David Ahern <dsahern@gmail.com> Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> --- 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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