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IB/ipath: Fix a race where s_last is updated without lock held

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There is a small window where a send work queue entry could be
overwritten by ib_post_send() because s_last is updated before the
entry is read.

This patch closes the window by acquiring the lock and updating
the last send work queue entry index after reading the wr_id.

Signed-off-by: Ralph Campbell <ralph.campbell@qlogic.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
This commit is contained in:
Ralph Campbell 2007-10-19 15:04:10 -07:00 committed by Roland Dreier
parent 96db0e0335
commit fffbfeaa68
1 changed files with 9 additions and 5 deletions
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14
drivers/infiniband/hw/ipath/ipath_ruc.c
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@ -630,11 +630,8 @@ bail:;
void ipath_send_complete(struct ipath_qp *qp, struct ipath_swqe *wqe,
enum ib_wc_status status)
{
u32 last = qp->s_last;
if (++last == qp->s_size)
last = 0;
qp->s_last = last;
unsigned long flags;
u32 last;
/* See ch. 11.2.4.1 and 10.7.3.1 */
if (!(qp->s_flags & IPATH_S_SIGNAL_REQ_WR) ||
@ -658,4 +655,11 @@ void ipath_send_complete(struct ipath_qp *qp, struct ipath_swqe *wqe,
wc.port_num = 0;
ipath_cq_enter(to_icq(qp->ibqp.send_cq), &wc, 0);
}
spin_lock_irqsave(&qp->s_lock, flags);
last = qp->s_last;
if (++last >= qp->s_size)
last = 0;
qp->s_last = last;
spin_unlock_irqrestore(&qp->s_lock, flags);
}