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author | Tejun Heo <tj@kernel.org> | 2008-09-24 16:22:23 -0500 |
---|---|---|
committer | Eric Van Hensbergen <ericvh@ericvh-desktop.austin.ibm.com> | 2008-09-24 16:22:23 -0500 |
commit | 7dc5d24be06a5ed874af035d52a083a7b61ef1bd (patch) | |
tree | 74f8e59f6a32ffc099dca3eb1eed9d6e6b58b616 /net/9p | |
parent | 72029fe85d8d060b3f966f2dbc36b3c75b5a6532 (diff) | |
download | linux-stable-7dc5d24be06a5ed874af035d52a083a7b61ef1bd.tar.gz linux-stable-7dc5d24be06a5ed874af035d52a083a7b61ef1bd.tar.bz2 linux-stable-7dc5d24be06a5ed874af035d52a083a7b61ef1bd.zip |
9p-trans_fd: fix trans_fd::p9_conn_destroy()
p9_conn_destroy() first kills all current requests by calling
p9_conn_cancel(), then waits for the request list to be cleared by
waiting on p9_conn->equeue. After that, polling is stopped and the
trans is destroyed. This sequence has a few problems.
* Read and write works were never cancelled and the p9_conn can be
destroyed while the works are running as r/w works remove requests
from the list and dereference the p9_conn from them.
* The list emptiness wait using p9_conn->equeue wouldn't trigger
because p9_conn_cancel() always clears all the lists and the only
way the wait can be triggered is to have another task to issue a
request between the slim window between p9_conn_cancel() and the
wait, which isn't safe under the current implementation with or
without the wait.
This patch fixes the problem by first stopping poll, which can
schedule r/w works, first and cancle r/w works which guarantees that
r/w works are not and will not run from that point and then calling
p9_conn_cancel() and do the rest of destruction.
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Eric Van Hensbergen <ericvh@gmail.com>
Diffstat (limited to 'net/9p')
-rw-r--r-- | net/9p/trans_fd.c | 24 |
1 files changed, 5 insertions, 19 deletions
diff --git a/net/9p/trans_fd.c b/net/9p/trans_fd.c index 6a32ffdb9429..ee0d151da31a 100644 --- a/net/9p/trans_fd.c +++ b/net/9p/trans_fd.c @@ -151,7 +151,6 @@ struct p9_mux_poll_task { * @trans: reference to transport instance for this connection * @tagpool: id accounting for transactions * @err: error state - * @equeue: event wait_q (?) * @req_list: accounting for requests which have been sent * @unsent_req_list: accounting for requests that haven't been sent * @rcall: current response &p9_fcall structure @@ -178,7 +177,6 @@ struct p9_conn { struct p9_trans *trans; struct p9_idpool *tagpool; int err; - wait_queue_head_t equeue; struct list_head req_list; struct list_head unsent_req_list; struct p9_fcall *rcall; @@ -430,7 +428,6 @@ static struct p9_conn *p9_conn_create(struct p9_trans *trans) } m->err = 0; - init_waitqueue_head(&m->equeue); INIT_LIST_HEAD(&m->req_list); INIT_LIST_HEAD(&m->unsent_req_list); m->rcall = NULL; @@ -483,18 +480,13 @@ static void p9_conn_destroy(struct p9_conn *m) { P9_DPRINTK(P9_DEBUG_MUX, "mux %p prev %p next %p\n", m, m->mux_list.prev, m->mux_list.next); - p9_conn_cancel(m, -ECONNRESET); - - if (!list_empty(&m->req_list)) { - /* wait until all processes waiting on this session exit */ - P9_DPRINTK(P9_DEBUG_MUX, - "mux %p waiting for empty request queue\n", m); - wait_event_timeout(m->equeue, (list_empty(&m->req_list)), 5000); - P9_DPRINTK(P9_DEBUG_MUX, "mux %p request queue empty: %d\n", m, - list_empty(&m->req_list)); - } p9_mux_poll_stop(m); + cancel_work_sync(&m->rq); + cancel_work_sync(&m->wq); + + p9_conn_cancel(m, -ECONNRESET); + m->trans = NULL; p9_idpool_destroy(m->tagpool); kfree(m); @@ -840,8 +832,6 @@ static void p9_read_work(struct work_struct *work) (*req->cb) (req, req->cba); else kfree(req->rcall); - - wake_up(&m->equeue); } } else { if (err >= 0 && rcall->id != P9_RFLUSH) @@ -984,8 +974,6 @@ static void p9_mux_flush_cb(struct p9_req *freq, void *a) (*req->cb) (req, req->cba); else kfree(req->rcall); - - wake_up(&m->equeue); } kfree(freq->tcall); @@ -1191,8 +1179,6 @@ void p9_conn_cancel(struct p9_conn *m, int err) else kfree(req->rcall); } - - wake_up(&m->equeue); } /** |