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authorDipankar Sarma <dipankar@in.ibm.com>2006-04-19 17:00:12 +0000
committerGreg Kroah-Hartman <gregkh@suse.de>2006-04-24 09:56:05 -0700
commit95fb678bf90572414b1c2f239c6a44226049ba8a (patch)
treeb7246d566793a2672111c598a450ba98fdc55b4e /fs/locks.c
parentbd6b6027eacb8e5ef633aa0e1c2576dc5a464675 (diff)
[PATCH] Fix file lookup without ref
There are places in the kernel where we look up files in fd tables and access the file structure without holding refereces to the file. So, we need special care to avoid the race between looking up files in the fd table and tearing down of the file in another CPU. Otherwise, one might see a NULL f_dentry or such torn down version of the file. This patch fixes those special places where such a race may happen. Signed-off-by: Dipankar Sarma <dipankar@in.ibm.com> Acked-by: "Paul E. McKenney" <paulmck@us.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'fs/locks.c')
-rw-r--r--fs/locks.c9
1 files changed, 7 insertions, 2 deletions
diff --git a/fs/locks.c b/fs/locks.c
index 909eab8fb1d..e75ac392a31 100644
--- a/fs/locks.c
+++ b/fs/locks.c
@@ -2212,7 +2212,12 @@ void steal_locks(fl_owner_t from)
lock_kernel();
j = 0;
- rcu_read_lock();
+
+ /*
+ * We are not taking a ref to the file structures, so
+ * we need to acquire ->file_lock.
+ */
+ spin_lock(&files->file_lock);
fdt = files_fdtable(files);
for (;;) {
unsigned long set;
@@ -2230,7 +2235,7 @@ void steal_locks(fl_owner_t from)
set >>= 1;
}
}
- rcu_read_unlock();
+ spin_unlock(&files->file_lock);
unlock_kernel();
}
EXPORT_SYMBOL(steal_locks);