IB/rdmavt: add lock to call to rvt_error_qp to prevent a race condition

stable inclusion
from stable-v5.10.111
commit 43c2d7890ecabe527448a6c391fb2d9a5e6bbfe0
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I5GL1Z

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=43c2d7890ecabe527448a6c391fb2d9a5e6bbfe0

--------------------------------

[ Upstream commit 4d809f69 ]

The documentation of the function rvt_error_qp says both r_lock and s_lock
need to be held when calling that function.  It also asserts using lockdep
that both of those locks are held.  However, the commit I referenced in
Fixes accidentally makes the call to rvt_error_qp in rvt_ruc_loopback no
longer covered by r_lock.  This results in the lockdep assertion failing
and also possibly in a race condition.

Fixes: d757c60e ("IB/rdmavt: Fix concurrency panics in QP post_send and modify to error")
Link: https://lore.kernel.org/r/20220228165330.41546-1-dossche.niels@gmail.comSigned-off-by: NNiels Dossche <dossche.niels@gmail.com>
Acked-by: NDennis Dalessandro <dennis.dalessandro@cornelisnetworks.com>
Signed-off-by: NJason Gunthorpe <jgg@nvidia.com>
Signed-off-by: NSasha Levin <sashal@kernel.org>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>
Reviewed-by: NWei Li <liwei391@huawei.com>

drivers/infiniband/sw/rdmavt/qp.c

@@ -3241,7 +3241,11 @@ void rvt_ruc_loopback(struct rvt_qp *sqp)
 	spin_lock_irqsave(&sqp->s_lock, flags);
 	rvt_send_complete(sqp, wqe, send_status);
 	if (sqp->ibqp.qp_type == IB_QPT_RC) {
-		int lastwqe = rvt_error_qp(sqp, IB_WC_WR_FLUSH_ERR);
+		int lastwqe;
+
+		spin_lock(&sqp->r_lock);
+		lastwqe = rvt_error_qp(sqp, IB_WC_WR_FLUSH_ERR);
+		spin_unlock(&sqp->r_lock);
 
 		sqp->s_flags &= ~RVT_S_BUSY;
 		spin_unlock_irqrestore(&sqp->s_lock, flags);