RDMA/cm: Fix IRQ restore in ib_send_cm_sidr_rep

ib_send_cm_sidr_rep() {
	spin_lock_irqsave()
        cm_send_sidr_rep_locked() {
                ...
        	spin_lock_irq()
                ....
                spin_unlock_irq() <--- this will enable interrupts
        }
        spin_unlock_irqrestore()
}

spin_unlock_irqrestore() expects interrupts to be disabled but the
internal spin_unlock_irq() will always enable hard interrupts.

Fix this by replacing the internal spin_{lock,unlock}_irq() with
irqsave/restore variants.

It fixes the following kernel trace:

 raw_local_irq_restore() called with IRQs enabled
 WARNING: CPU: 2 PID: 20001 at kernel/locking/irqflag-debug.c:10 warn_bogus_irq_restore+0x1d/0x20

 Call Trace:
  _raw_spin_unlock_irqrestore+0x4e/0x50
  ib_send_cm_sidr_rep+0x3a/0x50 [ib_cm]
  cma_send_sidr_rep+0xa1/0x160 [rdma_cm]
  rdma_accept+0x25e/0x350 [rdma_cm]
  ucma_accept+0x132/0x1cc [rdma_ucm]
  ucma_write+0xbf/0x140 [rdma_ucm]
  vfs_write+0xc1/0x340
  ksys_write+0xb3/0xe0
  do_syscall_64+0x2d/0x40
  entry_SYSCALL_64_after_hwframe+0x44/0xae

Fixes: 87c4c77 ("RDMA/cm: Protect access to remote_sidr_table")
Link: https://lore.kernel.org/r/20210301081844.445823-1-leon@kernel.org
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>

Author: Saeed Mahameed

drivers/infiniband/core/cm.c

@@ -3651,6 +3651,7 @@ static int cm_send_sidr_rep_locked(struct cm_id_private *cm_id_priv,
 				   struct ib_cm_sidr_rep_param *param)
 {
 	struct ib_mad_send_buf *msg;
+	unsigned long flags;
 	int ret;
 
 	lockdep_assert_held(&cm_id_priv->lock);
@@ -3676,12 +3677,12 @@ static int cm_send_sidr_rep_locked(struct cm_id_private *cm_id_priv,
 		return ret;
 	}
 	cm_id_priv->id.state = IB_CM_IDLE;
-	spin_lock_irq(&cm.lock);
+	spin_lock_irqsave(&cm.lock, flags);
 	if (!RB_EMPTY_NODE(&cm_id_priv->sidr_id_node)) {
 		rb_erase(&cm_id_priv->sidr_id_node, &cm.remote_sidr_table);
 		RB_CLEAR_NODE(&cm_id_priv->sidr_id_node);
 	}
-	spin_unlock_irq(&cm.lock);
+	spin_unlock_irqrestore(&cm.lock, flags);
 	return 0;
 }