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| author | Oleg Nesterov <oleg@redhat.com> | 2014-06-06 14:36:55 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2014-06-06 16:08:11 -0700 |
| commit | c240837fa7a7dd8cb3bef017ffb8af2c32cb0caf (patch) | |
| tree | b788451a3d45ad25aa5560af9c7e631f8892b671 /fs/jffs2 | |
| parent | 0341729b4b832e753c5e745c6ba0e797f6198be0 (diff) | |
| download | linux-c240837fa7a7dd8cb3bef017ffb8af2c32cb0caf.tar.bz2 | |
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@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Richard Weinberger <richard@nod.at>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs/jffs2')
| -rw-r--r-- | fs/jffs2/background.c | 12 |
1 files changed, 7 insertions, 5 deletions
diff --git a/fs/jffs2/background.c b/fs/jffs2/background.c index 2b60ce1996aa..bb9cebc9ca8a 100644 --- a/fs/jffs2/background.c +++ b/fs/jffs2/background.c @@ -75,10 +75,13 @@ void jffs2_stop_garbage_collect_thread(struct jffs2_sb_info *c) 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(void *_c) 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(void *_c) 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(void *_c) } } /* 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) { |