From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753429AbeENMmn (ORCPT ); Mon, 14 May 2018 08:42:43 -0400 Received: from terminus.zytor.com ([198.137.202.136]:54717 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753414AbeENMml (ORCPT ); Mon, 14 May 2018 08:42:41 -0400 Date: Mon, 14 May 2018 05:42:18 -0700 From: tip-bot for Dave Hansen Message-ID: Cc: shuah@kernel.org, hpa@zytor.com, peterz@infradead.org, dave.hansen@intel.com, mpe@ellerman.id.au, dave.hansen@linux.intel.com, linux-kernel@vger.kernel.org, torvalds@linux-foundation.org, mingo@kernel.org, tglx@linutronix.de, akpm@linux-foundation.org, linuxram@us.ibm.com Reply-To: dave.hansen@intel.com, mpe@ellerman.id.au, peterz@infradead.org, shuah@kernel.org, hpa@zytor.com, akpm@linux-foundation.org, linuxram@us.ibm.com, tglx@linutronix.de, mingo@kernel.org, torvalds@linux-foundation.org, linux-kernel@vger.kernel.org, dave.hansen@linux.intel.com In-Reply-To: <20180509171344.C53FD2F3@viggo.jf.intel.com> References: <20180509171344.C53FD2F3@viggo.jf.intel.com> To: linux-tip-commits@vger.kernel.org Subject: [tip:x86/urgent] x86/pkeys/selftests: Avoid printf-in-signal deadlocks Git-Commit-ID: caf9eb6b4c82fc6cbd03697052ff22d97b0c377b X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: caf9eb6b4c82fc6cbd03697052ff22d97b0c377b Gitweb: https://git.kernel.org/tip/caf9eb6b4c82fc6cbd03697052ff22d97b0c377b Author: Dave Hansen AuthorDate: Wed, 9 May 2018 10:13:44 -0700 Committer: Ingo Molnar CommitDate: Mon, 14 May 2018 11:14:45 +0200 x86/pkeys/selftests: Avoid printf-in-signal deadlocks printf() and friends are unusable in signal handlers. They deadlock. The pkey selftest does not do any normal printing in signal handlers, only extra debugging. So, just print the format string so we get *some* output when debugging. Signed-off-by: Dave Hansen Cc: Andrew Morton Cc: Dave Hansen Cc: Linus Torvalds Cc: Michael Ellermen Cc: Peter Zijlstra Cc: Ram Pai Cc: Shuah Khan Cc: Thomas Gleixner Cc: linux-mm@kvack.org Link: http://lkml.kernel.org/r/20180509171344.C53FD2F3@viggo.jf.intel.com Signed-off-by: Ingo Molnar --- tools/testing/selftests/x86/pkey-helpers.h | 20 ++++++++------------ 1 file changed, 8 insertions(+), 12 deletions(-) diff --git a/tools/testing/selftests/x86/pkey-helpers.h b/tools/testing/selftests/x86/pkey-helpers.h index b3cb7670e026..254e5436bdd9 100644 --- a/tools/testing/selftests/x86/pkey-helpers.h +++ b/tools/testing/selftests/x86/pkey-helpers.h @@ -26,30 +26,26 @@ static inline void sigsafe_printf(const char *format, ...) { va_list ap; - va_start(ap, format); if (!dprint_in_signal) { + va_start(ap, format); vprintf(format, ap); + va_end(ap); } else { int ret; - int len = vsnprintf(dprint_in_signal_buffer, - DPRINT_IN_SIGNAL_BUF_SIZE, - format, ap); /* - * len is amount that would have been printed, - * but actual write is truncated at BUF_SIZE. + * No printf() functions are signal-safe. + * They deadlock easily. Write the format + * string to get some output, even if + * incomplete. */ - if (len > DPRINT_IN_SIGNAL_BUF_SIZE) - len = DPRINT_IN_SIGNAL_BUF_SIZE; - ret = write(1, dprint_in_signal_buffer, len); + ret = write(1, format, strlen(format)); if (ret < 0) - abort(); + exit(1); } - va_end(ap); } #define dprintf_level(level, args...) do { \ if (level <= DEBUG_LEVEL) \ sigsafe_printf(args); \ - fflush(NULL); \ } while (0) #define dprintf0(args...) dprintf_level(0, args) #define dprintf1(args...) dprintf_level(1, args)