From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759099Ab3K1Po2 (ORCPT ); Thu, 28 Nov 2013 10:44:28 -0500 Received: from mx1.redhat.com ([209.132.183.28]:62340 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755611Ab3K1PoY (ORCPT ); Thu, 28 Nov 2013 10:44:24 -0500 Date: Thu, 28 Nov 2013 16:43:50 +0100 From: Jiri Olsa To: David Ahern Cc: linux-kernel@vger.kernel.org, Ingo Molnar , Frederic Weisbecker , Peter Zijlstra , Namhyung Kim , Mike Galbraith , Adrian Hunter , Arnaldo Carvalho de Melo Subject: [PATCHv3 3/7] perf tools: Fine tune readn function Message-ID: <20131128154350.GB31444@krava.brq.redhat.com> References: <1385634619-8129-1-git-send-email-jolsa@redhat.com> <1385634619-8129-4-git-send-email-jolsa@redhat.com> <52975F17.2050402@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <52975F17.2050402@gmail.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 Signed-off-by: Jiri Olsa Cc: Ingo Molnar Cc: Frederic Weisbecker Cc: Peter Zijlstra Cc: Namhyung Kim Cc: Mike Galbraith Cc: David Ahern Cc: Adrian Hunter Cc: Arnaldo Carvalho de Melo --- 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 #include +#include +#include /* * 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