Subject: [merged] signals-jffs2-fix-the-wrong-usage-of-disallow_signal.patch removed from -mm tree To: oleg@xxxxxxxxxx,dwmw2@xxxxxxxxxxxxx,fweisbec@xxxxxxxxx,geert@xxxxxxxxxxxxxx,mathieu.desnoyers@xxxxxxxxxxxx,mingo@xxxxxxxxxx,peterz@xxxxxxxxxxxxx,richard@xxxxxx,rostedt@xxxxxxxxxxx,tj@xxxxxxxxxx,viro@xxxxxxxxxxxxxxxxxx,mm-commits@xxxxxxxxxxxxxxx From: akpm@xxxxxxxxxxxxxxxxxxxx Date: Mon, 09 Jun 2014 12:34:07 -0700 The patch titled Subject: signals: jffs2: fix the wrong usage of disallow_signal() has been removed from the -mm tree. Its filename was signals-jffs2-fix-the-wrong-usage-of-disallow_signal.patch This patch was dropped because it was merged into mainline or a subsystem tree ------------------------------------------------------ From: Oleg Nesterov <oleg@xxxxxxxxxx> Subject: signals: jffs2: fix the wrong usage of disallow_signal() jffs2_garbage_collect_thread() does disallow_signal(SIGHUP) around jffs2_garbage_collect_pass() and the comment says "We don't want SIGHUP to interrupt us". But disallow_signal() can't ensure that jffs2_garbage_collect_pass() won't be interrupted by SIGHUP, the problem is that SIGHUP can be already pending when disallow_signal() is called, and in this case any interruptible sleep won't block. Note: this is in fact because disallow_signal() is buggy and should be fixed, see the next changes. But there is another reason why disallow_signal() is wrong: SIG_IGN set by disallow_signal() silently discards any SIGHUP which can be sent before the next allow_signal(SIGHUP). Change this code to use sigprocmask(SIG_UNBLOCK/SIG_BLOCK, SIGHUP). This even matches the old (and wrong) semantics allow/disallow had when this logic was written. Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx> Cc: David Woodhouse <dwmw2@xxxxxxxxxxxxx> Cc: Frederic Weisbecker <fweisbec@xxxxxxxxx> Cc: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx> Cc: Ingo Molnar <mingo@xxxxxxxxxx> Cc: Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxxxx> Cc: Richard Weinberger <richard@xxxxxx> Cc: Steven Rostedt <rostedt@xxxxxxxxxxx> Cc: Tejun Heo <tj@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- fs/jffs2/background.c | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-) diff -puN fs/jffs2/background.c~signals-jffs2-fix-the-wrong-usage-of-disallow_signal fs/jffs2/background.c --- a/fs/jffs2/background.c~signals-jffs2-fix-the-wrong-usage-of-disallow_signal +++ a/fs/jffs2/background.c @@ -75,10 +75,13 @@ void jffs2_stop_garbage_collect_thread(s static int jffs2_garbage_collect_thread(void *_c) { struct jffs2_sb_info *c = _c; + sigset_t hupmask; + siginitset(&hupmask, sigmask(SIGHUP)); allow_signal(SIGKILL); allow_signal(SIGSTOP); allow_signal(SIGCONT); + allow_signal(SIGHUP); c->gc_task = current; complete(&c->gc_thread_start); @@ -87,7 +90,7 @@ static int jffs2_garbage_collect_thread( set_freezable(); for (;;) { - allow_signal(SIGHUP); + sigprocmask(SIG_UNBLOCK, &hupmask, NULL); again: spin_lock(&c->erase_completion_lock); if (!jffs2_thread_should_wake(c)) { @@ -95,10 +98,9 @@ static int jffs2_garbage_collect_thread( spin_unlock(&c->erase_completion_lock); jffs2_dbg(1, "%s(): sleeping...\n", __func__); schedule(); - } else + } else { spin_unlock(&c->erase_completion_lock); - - + } /* Problem - immediately after bootup, the GCD spends a lot * of time in places like jffs2_kill_fragtree(); so much so * that userspace processes (like gdm and X) are starved @@ -150,7 +152,7 @@ static int jffs2_garbage_collect_thread( } } /* We don't want SIGHUP to interrupt us. STOP and KILL are OK though. */ - disallow_signal(SIGHUP); + sigprocmask(SIG_BLOCK, &hupmask, NULL); jffs2_dbg(1, "%s(): pass\n", __func__); if (jffs2_garbage_collect_pass(c) == -ENOSPC) { _ Patches currently in -mm which might be from oleg@xxxxxxxxxx are origin.patch cpu-hotplug-smp-flush-any-pending-ipi-callbacks-before-cpu-offline.patch linux-next.patch kernel-watchdogc-print-traces-for-all-cpus-on-lockup-detection.patch kernel-watchdogc-print-traces-for-all-cpus-on-lockup-detection-fix.patch nmi-provide-the-option-to-issue-an-nmi-back-trace-to-every-cpu-but-current.patch nmi-provide-the-option-to-issue-an-nmi-back-trace-to-every-cpu-but-current-fix.patch -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html