Commit 605b0487 authored Mar 06, 2019 by Andreas Gruenbacher

gfs2: Fix missed wakeups in find_insert_glock



Mark Syms has reported seeing tasks that are stuck waiting in
find_insert_glock.  It turns out that struct lm_lockname contains four padding
bytes on 64-bit architectures that function glock_waitqueue doesn't skip when
hashing the glock name.  As a result, we can end up waking up the wrong
waitqueue, and the waiting tasks may be stuck forever.

Fix that by using ht_parms.key_len instead of sizeof(struct lm_lockname) for
the key length.

Reported-by: Mark Syms <mark.syms@citrix.com>
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Signed-off-by: Bob Peterson <rpeterso@redhat.com>

parent 7c03e756

fs/gfs2/glock.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -107,7 +107,7 @@ static int glock_wake_function(wait_queue_entry_t *wait, unsigned int mode,

		static wait_queue_head_t glock_waitqueue(struct lm_lockname name)
		{
		u32 hash = jhash2((u32 )name, sizeof(name) / 4, 0);
		u32 hash = jhash2((u32 *)name, ht_parms.key_len / 4, 0);

		return glock_wait_table + hash_32(hash, GLOCK_WAIT_TABLE_BITS);
		}

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