From 00f89d218523b9bf6b522349c039d5ac80aa536d Mon Sep 17 00:00:00 2001 From: Oleg Nesterov Date: Fri, 10 Jul 2009 03:27:38 +0200 Subject: mm_for_maps: shift down_read(mmap_sem) to the caller mm_for_maps() takes ->mmap_sem after security checks, this looks strange and obfuscates the locking rules. Move this lock to its single caller, m_start(). Signed-off-by: Oleg Nesterov Acked-by: Serge Hallyn Signed-off-by: James Morris --- fs/proc/base.c | 8 +++----- 1 file changed, 3 insertions(+), 5 deletions(-) (limited to 'fs/proc/base.c') diff --git a/fs/proc/base.c b/fs/proc/base.c index 917f338a6739..f3c2e4085fed 100644 --- a/fs/proc/base.c +++ b/fs/proc/base.c @@ -235,9 +235,8 @@ static int check_mem_permission(struct task_struct *task) struct mm_struct *mm_for_maps(struct task_struct *task) { struct mm_struct *mm = get_task_mm(task); - if (!mm) - return NULL; - if (mm != current->mm) { + + if (mm && mm != current->mm) { /* * task->mm can be changed before security check, * in that case we must notice the change after. @@ -245,10 +244,9 @@ struct mm_struct *mm_for_maps(struct task_struct *task) if (!ptrace_may_access(task, PTRACE_MODE_READ) || mm != task->mm) { mmput(mm); - return NULL; + mm = NULL; } } - down_read(&mm->mmap_sem); return mm; } -- cgit v1.2.2