Messages in this thread Patch in this message | | | Date | Tue, 15 Jul 2008 18:07:15 +0400 | From | Oleg Nesterov <> | Subject | [PATCH] coredump: kill mm->core_done |
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Now that we have core_state->dumper list we can use it to wake up the sub-threads waiting for the coredump completion.
This uglifies the code and .text grows by 47 bytes, but otoh mm_struct lessens by sizeof(struct completion). Also, with this change we can decouple exit_mm() from the coredumping code.
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
include/linux/mm_types.h | 4 +--- kernel/exit.c | 8 +++++++- fs/exec.c | 25 ++++++++++++++++++++++--- 3 files changed, 30 insertions(+), 7 deletions(-)
--- 26-rc2/include/linux/mm_types.h~5_KILL_CORE_DONE 2008-07-13 18:28:36.000000000 +0400 +++ 26-rc2/include/linux/mm_types.h 2008-07-15 17:06:58.000000000 +0400 @@ -229,9 +229,7 @@ struct mm_struct { unsigned long flags; /* Must use atomic bitops to access the bits */ - /* coredumping support */ - struct core_state *core_state; - struct completion core_done; + struct core_state *core_state; /* coredumping support */ /* aio bits */ rwlock_t ioctx_list_lock; /* aio lock */ --- 26-rc2/kernel/exit.c~5_KILL_CORE_DONE 2008-07-13 19:58:19.000000000 +0400 +++ 26-rc2/kernel/exit.c 2008-07-15 17:06:58.000000000 +0400 @@ -680,7 +680,13 @@ static void exit_mm(struct task_struct * if (atomic_dec_and_test(&core_state->nr_threads)) complete(&core_state->startup); - wait_for_completion(&mm->core_done); + for (;;) { + set_task_state(tsk, TASK_UNINTERRUPTIBLE); + if (!self.task) /* see coredump_finish() */ + break; + schedule(); + } + __set_task_state(tsk, TASK_UNINTERRUPTIBLE); down_read(&mm->mmap_sem); } atomic_inc(&mm->mm_count); --- 26-rc2/fs/exec.c~5_KILL_CORE_DONE 2008-07-13 18:43:39.000000000 +0400 +++ 26-rc2/fs/exec.c 2008-07-15 17:54:45.000000000 +0400 @@ -1597,7 +1597,6 @@ static int coredump_wait(int exit_code, struct completion *vfork_done; int core_waiters; - init_completion(&mm->core_done); init_completion(&core_state->startup); core_state->dumper.task = tsk; core_state->dumper.next = NULL; @@ -1623,6 +1622,27 @@ fail: return core_waiters; } +static void coredump_finish(struct mm_struct *mm) +{ + struct core_thread *curr, *next; + struct task_struct *task; + + next = mm->core_state->dumper.next; + while ((curr = next) != NULL) { + next = curr->next; + task = curr->task; + /* + * see exit_mm(), curr->task must not see + * ->task == NULL before we read ->next. + */ + smp_mb(); + curr->task = NULL; + wake_up_process(task); + } + + mm->core_state = NULL; +} + /* * set_dumpable converts traditional three-value dumpable to two flags and * stores them into mm->flags. It modifies lower two bits of mm->flags, but @@ -1807,8 +1827,7 @@ fail_unlock: argv_free(helper_argv); current->fsuid = fsuid; - complete_all(&mm->core_done); - mm->core_state = NULL; + coredump_finish(mm); fail: return retval; }
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