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authorDominique Martinet <dominique.martinet@cea.fr>2014-01-17 18:31:00 +0100
committerEric Van Hensbergen <ericvh@gmail.com>2014-03-25 16:37:59 -0500
commit2b6e72ed747f68a038df616efd86744b3644d694 (patch)
treed781427484432608a74ccc44fd4a7a3296751f23 /net/9p/trans_fd.c
parent38dbfb59d1175ef458d006556061adeaa8751b72 (diff)
downloadlinux-2b6e72ed747f68a038df616efd86744b3644d694.tar.bz2
9P: Add memory barriers to protect request fields over cb/rpc threads handoff
We need barriers to guarantee this pattern works as intended: [w] req->rc, 1 [r] req->status, 1 wmb rmb [w] req->status, 1 [r] req->rc Where the wmb ensures that rc gets written before status, and the rmb ensures that if you observe status == 1, rc is the new value. Signed-off-by: Dominique Martinet <dominique.martinet@cea.fr> Signed-off-by: Eric Van Hensbergen <ericvh@gmail.com>
Diffstat (limited to 'net/9p/trans_fd.c')
-rw-r--r--net/9p/trans_fd.c15
1 files changed, 6 insertions, 9 deletions
diff --git a/net/9p/trans_fd.c b/net/9p/trans_fd.c
index b7bd7f2961bf..193efd562466 100644
--- a/net/9p/trans_fd.c
+++ b/net/9p/trans_fd.c
@@ -212,15 +212,9 @@ static void p9_conn_cancel(struct p9_conn *m, int err)
m->err = err;
list_for_each_entry_safe(req, rtmp, &m->req_list, req_list) {
- req->status = REQ_STATUS_ERROR;
- if (!req->t_err)
- req->t_err = err;
list_move(&req->req_list, &cancel_list);
}
list_for_each_entry_safe(req, rtmp, &m->unsent_req_list, req_list) {
- req->status = REQ_STATUS_ERROR;
- if (!req->t_err)
- req->t_err = err;
list_move(&req->req_list, &cancel_list);
}
spin_unlock_irqrestore(&m->client->lock, flags);
@@ -228,7 +222,9 @@ static void p9_conn_cancel(struct p9_conn *m, int err)
list_for_each_entry_safe(req, rtmp, &cancel_list, req_list) {
p9_debug(P9_DEBUG_ERROR, "call back req %p\n", req);
list_del(&req->req_list);
- p9_client_cb(m->client, req);
+ if (!req->t_err)
+ req->t_err = err;
+ p9_client_cb(m->client, req, REQ_STATUS_ERROR);
}
}
@@ -302,6 +298,7 @@ static void p9_read_work(struct work_struct *work)
{
int n, err;
struct p9_conn *m;
+ int status = REQ_STATUS_ERROR;
m = container_of(work, struct p9_conn, rq);
@@ -375,10 +372,10 @@ static void p9_read_work(struct work_struct *work)
p9_debug(P9_DEBUG_TRANS, "got new packet\n");
spin_lock(&m->client->lock);
if (m->req->status != REQ_STATUS_ERROR)
- m->req->status = REQ_STATUS_RCVD;
+ status = REQ_STATUS_RCVD;
list_del(&m->req->req_list);
spin_unlock(&m->client->lock);
- p9_client_cb(m->client, m->req);
+ p9_client_cb(m->client, m->req, status);
m->rbuf = NULL;
m->rpos = 0;
m->rsize = 0;