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| author | NeilBrown <neilb@suse.de> | 2010-11-15 11:27:01 +1100 |
|---|---|---|
| committer | J. Bruce Fields <bfields@redhat.com> | 2010-12-17 15:48:18 -0500 |
| commit | 7c96aef75949a56ec427fc6a2522dace2af33605 (patch) | |
| tree | ca65368231d4c5b39e3adce558bfe15d712809c7 /net/sunrpc/svc_xprt.c | |
| parent | 18b631f83810e95eeb2e1839889b27142bd8d6d8 (diff) | |
| download | lwn-7c96aef75949a56ec427fc6a2522dace2af33605.tar.gz lwn-7c96aef75949a56ec427fc6a2522dace2af33605.zip | |
sunrpc: remove xpt_pool
The xpt_pool field is only used for reporting BUGs.
And it isn't used correctly.
In particular, when it is cleared in svc_xprt_received before
XPT_BUSY is cleared, there is no guarantee that either the
compiler or the CPU might not re-order to two assignments, just
setting xpt_pool to NULL after XPT_BUSY is cleared.
If a different cpu were running svc_xprt_enqueue at this moment,
it might see XPT_BUSY clear and then xpt_pool non-NULL, and
so BUG.
This could be fixed by calling
smp_mb__before_clear_bit()
before the clear_bit. However as xpt_pool isn't really used,
it seems safest to simply remove xpt_pool.
Another alternate would be to change the clear_bit to
clear_bit_unlock, and the test_and_set_bit to test_and_set_bit_lock.
Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Diffstat (limited to 'net/sunrpc/svc_xprt.c')
| -rw-r--r-- | net/sunrpc/svc_xprt.c | 5 |
1 files changed, 0 insertions, 5 deletions
diff --git a/net/sunrpc/svc_xprt.c b/net/sunrpc/svc_xprt.c index 5a75d23645c8..5eae53b1e306 100644 --- a/net/sunrpc/svc_xprt.c +++ b/net/sunrpc/svc_xprt.c @@ -351,8 +351,6 @@ void svc_xprt_enqueue(struct svc_xprt *xprt) dprintk("svc: transport %p busy, not enqueued\n", xprt); goto out_unlock; } - BUG_ON(xprt->xpt_pool != NULL); - xprt->xpt_pool = pool; if (!list_empty(&pool->sp_threads)) { rqstp = list_entry(pool->sp_threads.next, @@ -370,13 +368,11 @@ void svc_xprt_enqueue(struct svc_xprt *xprt) rqstp->rq_reserved = serv->sv_max_mesg; atomic_add(rqstp->rq_reserved, &xprt->xpt_reserved); pool->sp_stats.threads_woken++; - BUG_ON(xprt->xpt_pool != pool); wake_up(&rqstp->rq_wait); } else { dprintk("svc: transport %p put into queue\n", xprt); list_add_tail(&xprt->xpt_ready, &pool->sp_sockets); pool->sp_stats.sockets_queued++; - BUG_ON(xprt->xpt_pool != pool); } out_unlock: @@ -415,7 +411,6 @@ static struct svc_xprt *svc_xprt_dequeue(struct svc_pool *pool) void svc_xprt_received(struct svc_xprt *xprt) { BUG_ON(!test_bit(XPT_BUSY, &xprt->xpt_flags)); - xprt->xpt_pool = NULL; /* As soon as we clear busy, the xprt could be closed and * 'put', so we need a reference to call svc_xprt_enqueue with: */ |