IB/ehca: Rework destroy_eq()

The ibmebus_free_irq() function, which might sleep, was called with
interrupts disabled.  To fix this, make sure that no interrupts are
running by killing the interrupt tasklet.  Also lock the
shca_list_lock to protect against the poll_eqs_timer running
concurrently.
Signed-off-by: Alexander Schmidt <alexs@linux.vnet.ibm.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>

drivers/infiniband/hw/ehca/ehca_classes.h

@@ -375,6 +375,7 @@ extern rwlock_t ehca_qp_idr_lock;
 extern rwlock_t ehca_cq_idr_lock;
 extern struct idr ehca_qp_idr;
 extern struct idr ehca_cq_idr;
+extern spinlock_t shca_list_lock;
 
 extern int ehca_static_rate;
 extern int ehca_port_act_time;

drivers/infiniband/hw/ehca/ehca_eq.c

@@ -169,12 +169,15 @@ int ehca_destroy_eq(struct ehca_shca *shca, struct ehca_eq *eq)
 	unsigned long flags;
 	u64 h_ret;
 
-	spin_lock_irqsave(&eq->spinlock, flags);
 	ibmebus_free_irq(eq->ist, (void *)shca);
 
-	h_ret = hipz_h_destroy_eq(shca->ipz_hca_handle, eq);
+	spin_lock_irqsave(&shca_list_lock, flags);
+	eq->is_initialized = 0;
+	spin_unlock_irqrestore(&shca_list_lock, flags);
 
-	spin_unlock_irqrestore(&eq->spinlock, flags);
+	tasklet_kill(&eq->interrupt_task);
+
+	h_ret = hipz_h_destroy_eq(shca->ipz_hca_handle, eq);
 
 	if (h_ret != H_SUCCESS) {
 		ehca_err(&shca->ib_device, "Can't free EQ resources.");

drivers/infiniband/hw/ehca/ehca_main.c

@@ -123,7 +123,7 @@ DEFINE_IDR(ehca_qp_idr);
 DEFINE_IDR(ehca_cq_idr);
 
 static LIST_HEAD(shca_list); /* list of all registered ehcas */
-static DEFINE_SPINLOCK(shca_list_lock);
+DEFINE_SPINLOCK(shca_list_lock);
 
 static struct timer_list poll_eqs_timer;