Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756313AbYF1NPn (ORCPT ); Sat, 28 Jun 2008 09:15:43 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753446AbYF1NOh (ORCPT ); Sat, 28 Jun 2008 09:14:37 -0400 Received: from x346.tv-sign.ru ([89.108.83.215]:44596 "EHLO mail.screens.ru" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753273AbYF1NOf (ORCPT ); Sat, 28 Jun 2008 09:14:35 -0400 Date: Sat, 28 Jun 2008 17:17:17 +0400 From: Oleg Nesterov To: Andrew Morton Cc: Roland McGrath , linux-kernel@vger.kernel.org Subject: [PATCH 2/4] coredump: move mm->core_waiters into struct core_state Message-ID: <20080628131717.GA4412@tv-sign.ru> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.5.11 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 6115 Lines: 172 Move mm->core_waiters into "struct core_state" allocated on stack. This shrinks mm_struct a little bit and allows further changes. This patch mostly does s/core_waiters/core_state. The only essential change is that coredump_wait() must clear mm->core_state before return. The coredump_wait()'s path is uglified and .text grows by 30 bytes, this is fixed by the next patch. Signed-off-by: Oleg Nesterov include/linux/mm_types.h | 2 +- kernel/fork.c | 2 +- kernel/signal.c | 4 ++-- kernel/exit.c | 8 ++++---- fs/exec.c | 21 +++++++++++---------- 5 files changed, 19 insertions(+), 18 deletions(-) --- 26-rc2/include/linux/mm_types.h~2_CORE_WAITERS 2008-06-15 14:23:40.000000000 +0400 +++ 26-rc2/include/linux/mm_types.h 2008-06-15 15:26:29.000000000 +0400 @@ -160,6 +160,7 @@ struct vm_area_struct { }; struct core_state { + int nr_threads; struct completion startup; }; @@ -179,7 +180,6 @@ struct mm_struct { atomic_t mm_users; /* How many users with user space? */ atomic_t mm_count; /* How many references to "struct mm_struct" (users count as 1) */ int map_count; /* number of VMAs */ - int core_waiters; struct rw_semaphore mmap_sem; spinlock_t page_table_lock; /* Protects page tables and some counters */ --- 26-rc2/kernel/fork.c~2_CORE_WAITERS 2008-06-01 16:44:39.000000000 +0400 +++ 26-rc2/kernel/fork.c 2008-06-15 15:32:10.000000000 +0400 @@ -373,7 +373,7 @@ static struct mm_struct * mm_init(struct INIT_LIST_HEAD(&mm->mmlist); mm->flags = (current->mm) ? current->mm->flags : MMF_DUMP_FILTER_DEFAULT; - mm->core_waiters = 0; + mm->core_state = NULL; mm->nr_ptes = 0; set_mm_counter(mm, file_rss, 0); set_mm_counter(mm, anon_rss, 0); --- 26-rc2/kernel/signal.c~ 2008-06-28 16:06:07.000000000 +0400 +++ 26-rc2/kernel/signal.c 2008-06-28 17:06:58.000000000 +0400 @@ -1482,10 +1482,10 @@ static inline int may_ptrace_stop(void) * is a deadlock situation, and pointless because our tracer * is dead so don't allow us to stop. * If SIGKILL was already sent before the caller unlocked - * ->siglock we must see ->core_waiters != 0. Otherwise it + * ->siglock we must see ->core_state != NULL. Otherwise it * is safe to enter schedule(). */ - if (unlikely(current->mm->core_waiters) && + if (unlikely(current->mm->core_state) && unlikely(current->mm == current->parent->mm)) return 0; --- 26-rc2/kernel/exit.c~2_CORE_WAITERS 2008-06-15 14:24:35.000000000 +0400 +++ 26-rc2/kernel/exit.c 2008-06-15 15:28:21.000000000 +0400 @@ -659,16 +659,16 @@ static void exit_mm(struct task_struct * return; /* * Serialize with any possible pending coredump. - * We must hold mmap_sem around checking core_waiters + * We must hold mmap_sem around checking core_state * and clearing tsk->mm. The core-inducing thread - * will increment core_waiters for each thread in the + * will increment ->nr_threads for each thread in the * group with ->mm != NULL. */ down_read(&mm->mmap_sem); - if (mm->core_waiters) { + if (mm->core_state) { up_read(&mm->mmap_sem); down_write(&mm->mmap_sem); - if (!--mm->core_waiters) + if (!--mm->core_state->nr_threads) complete(&mm->core_state->startup); up_write(&mm->mmap_sem); --- 26-rc2/fs/exec.c~2_CORE_WAITERS 2008-06-15 14:25:44.000000000 +0400 +++ 26-rc2/fs/exec.c 2008-06-16 16:50:13.000000000 +0400 @@ -720,12 +720,10 @@ static int exec_mmap(struct mm_struct *m * Make sure that if there is a core dump in progress * for the old mm, we get out and die instead of going * through with the exec. We must hold mmap_sem around - * checking core_waiters and changing tsk->mm. The - * core-inducing thread will increment core_waiters for - * each thread whose ->mm == old_mm. + * checking core_state and changing tsk->mm. */ down_read(&old_mm->mmap_sem); - if (unlikely(old_mm->core_waiters)) { + if (unlikely(old_mm->core_state)) { up_read(&old_mm->mmap_sem); return -EINTR; } @@ -1508,7 +1506,7 @@ static void zap_process(struct task_stru t = start; do { if (t != current && t->mm) { - t->mm->core_waiters++; + t->mm->core_state->nr_threads++; sigaddset(&t->pending.signal, SIGKILL); signal_wake_up(t, 1); } @@ -1532,11 +1530,11 @@ static inline int zap_threads(struct tas if (err) return err; - if (atomic_read(&mm->mm_users) == mm->core_waiters + 1) + if (atomic_read(&mm->mm_users) == mm->core_state->nr_threads + 1) goto done; /* * We should find and kill all tasks which use this mm, and we should - * count them correctly into mm->core_waiters. We don't take tasklist + * count them correctly into ->nr_threads. We don't take tasklist * lock, but this is safe wrt: * * fork: @@ -1585,7 +1583,7 @@ static inline int zap_threads(struct tas } rcu_read_unlock(); done: - return mm->core_waiters; + return mm->core_state->nr_threads; } static int coredump_wait(int exit_code) @@ -1598,9 +1596,12 @@ static int coredump_wait(int exit_code) init_completion(&mm->core_done); init_completion(&core_state.startup); + core_state.nr_threads = 0; mm->core_state = &core_state; core_waiters = zap_threads(tsk, mm, exit_code); + if (core_waiters < 0) + mm->core_state = NULL; up_write(&mm->mmap_sem); if (unlikely(core_waiters < 0)) @@ -1618,8 +1619,8 @@ static int coredump_wait(int exit_code) if (core_waiters) wait_for_completion(&core_state.startup); + mm->core_state = NULL; fail: - BUG_ON(mm->core_waiters); return core_waiters; } @@ -1697,7 +1698,7 @@ int do_coredump(long signr, int exit_cod /* * If another thread got here first, or we are not dumpable, bail out. */ - if (mm->core_waiters || !get_dumpable(mm)) { + if (mm->core_state || !get_dumpable(mm)) { up_write(&mm->mmap_sem); goto fail; } -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/