IB/ehca: Change idr spinlocks into rwlocks

This eliminates lock contention among IRQs as well as the need to
disable IRQs around idr_find, because there are no IRQ writers.

Signed-off-by: Joachim Fenkes <fenkes@de.ibm.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>

6 files changed, 28 insertions, 32 deletions

diff --git a/drivers/infiniband/hw/ehca/ehca_classes.h b/drivers/infiniband/hw/ehca/ehca_classes.h
index 8580f2a0ea57..f1e0db2ff16c 100644
--- a/drivers/infiniband/hw/ehca/ehca_classes.h
+++ b/drivers/infiniband/hw/ehca/ehca_classes.h
@@ -293,8 +293,8 @@ void ehca_cleanup_av_cache(void);
 int ehca_init_mrmw_cache(void);
 void ehca_cleanup_mrmw_cache(void);
 
-extern spinlock_t ehca_qp_idr_lock;
-extern spinlock_t ehca_cq_idr_lock;
+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;
 
diff --git a/drivers/infiniband/hw/ehca/ehca_cq.c b/drivers/infiniband/hw/ehca/ehca_cq.c
index 3729997457ca..01d4a148bd71 100644
--- a/drivers/infiniband/hw/ehca/ehca_cq.c
+++ b/drivers/infiniband/hw/ehca/ehca_cq.c
@@ -163,9 +163,9 @@ struct ib_cq *ehca_create_cq(struct ib_device *device, int cqe, int comp_vector,
                         goto create_cq_exit1;
                 }
 
-                spin_lock_irqsave(&ehca_cq_idr_lock, flags);
+                write_lock_irqsave(&ehca_cq_idr_lock, flags);
                 ret = idr_get_new(&ehca_cq_idr, my_cq, &my_cq->token);
-                spin_unlock_irqrestore(&ehca_cq_idr_lock, flags);
+                write_unlock_irqrestore(&ehca_cq_idr_lock, flags);
 
         } while (ret == -EAGAIN);
 
@@ -294,9 +294,9 @@ create_cq_exit3:
                          "cq_num=%x h_ret=%lx", my_cq, my_cq->cq_number, h_ret);
 
 create_cq_exit2:
-        spin_lock_irqsave(&ehca_cq_idr_lock, flags);
+        write_lock_irqsave(&ehca_cq_idr_lock, flags);
         idr_remove(&ehca_cq_idr, my_cq->token);
-        spin_unlock_irqrestore(&ehca_cq_idr_lock, flags);
+        write_unlock_irqrestore(&ehca_cq_idr_lock, flags);
 
 create_cq_exit1:
         kmem_cache_free(cq_cache, my_cq);
@@ -334,9 +334,9 @@ int ehca_destroy_cq(struct ib_cq *cq)
          * remove the CQ from the idr first to make sure
          * no more interrupt tasklets will touch this CQ
          */
-        spin_lock_irqsave(&ehca_cq_idr_lock, flags);
+        write_lock_irqsave(&ehca_cq_idr_lock, flags);
         idr_remove(&ehca_cq_idr, my_cq->token);
-        spin_unlock_irqrestore(&ehca_cq_idr_lock, flags);
+        write_unlock_irqrestore(&ehca_cq_idr_lock, flags);
 
         /* now wait until all pending events have completed */
         wait_event(my_cq->wait_completion, !atomic_read(&my_cq->nr_events));
diff --git a/drivers/infiniband/hw/ehca/ehca_irq.c b/drivers/infiniband/hw/ehca/ehca_irq.c
index 3e790a326d97..02b73c84c49b 100644
--- a/drivers/infiniband/hw/ehca/ehca_irq.c
+++ b/drivers/infiniband/hw/ehca/ehca_irq.c
@@ -180,12 +180,11 @@ static void qp_event_callback(struct ehca_shca *shca,
 {
         struct ib_event event;
         struct ehca_qp *qp;
-        unsigned long flags;
         u32 token = EHCA_BMASK_GET(EQE_QP_TOKEN, eqe);
 
-        spin_lock_irqsave(&ehca_qp_idr_lock, flags);
+        read_lock(&ehca_qp_idr_lock);
         qp = idr_find(&ehca_qp_idr, token);
-        spin_unlock_irqrestore(&ehca_qp_idr_lock, flags);
+        read_unlock(&ehca_qp_idr_lock);
 
 
         if (!qp)
@@ -209,14 +208,13 @@ static void cq_event_callback(struct ehca_shca *shca,
                               u64 eqe)
 {
         struct ehca_cq *cq;
-        unsigned long flags;
         u32 token = EHCA_BMASK_GET(EQE_CQ_TOKEN, eqe);
 
-        spin_lock_irqsave(&ehca_cq_idr_lock, flags);
+        read_lock(&ehca_cq_idr_lock);
         cq = idr_find(&ehca_cq_idr, token);
         if (cq)
                 atomic_inc(&cq->nr_events);
-        spin_unlock_irqrestore(&ehca_cq_idr_lock, flags);
+        read_unlock(&ehca_cq_idr_lock);
 
         if (!cq)
                 return;
@@ -411,7 +409,6 @@ static inline void process_eqe(struct ehca_shca *shca, struct ehca_eqe *eqe)
 {
         u64 eqe_value;
         u32 token;
-        unsigned long flags;
         struct ehca_cq *cq;
 
         eqe_value = eqe->entry;
@@ -419,11 +416,11 @@ static inline void process_eqe(struct ehca_shca *shca, struct ehca_eqe *eqe)
         if (EHCA_BMASK_GET(EQE_COMPLETION_EVENT, eqe_value)) {
                 ehca_dbg(&shca->ib_device, "Got completion event");
                 token = EHCA_BMASK_GET(EQE_CQ_TOKEN, eqe_value);
-                spin_lock_irqsave(&ehca_cq_idr_lock, flags);
+                read_lock(&ehca_cq_idr_lock);
                 cq = idr_find(&ehca_cq_idr, token);
                 if (cq)
                         atomic_inc(&cq->nr_events);
-                spin_unlock_irqrestore(&ehca_cq_idr_lock, flags);
+                read_unlock(&ehca_cq_idr_lock);
                 if (cq == NULL) {
                         ehca_err(&shca->ib_device,
                                  "Invalid eqe for non-existing cq token=%x",
@@ -480,11 +477,11 @@ void ehca_process_eq(struct ehca_shca *shca, int is_irq)
                 eqe_value = eqe_cache[eqe_cnt].eqe->entry;
                 if (EHCA_BMASK_GET(EQE_COMPLETION_EVENT, eqe_value)) {
                         token = EHCA_BMASK_GET(EQE_CQ_TOKEN, eqe_value);
-                        spin_lock(&ehca_cq_idr_lock);
+                        read_lock(&ehca_cq_idr_lock);
                         eqe_cache[eqe_cnt].cq = idr_find(&ehca_cq_idr, token);
                         if (eqe_cache[eqe_cnt].cq)
                                 atomic_inc(&eqe_cache[eqe_cnt].cq->nr_events);
-                        spin_unlock(&ehca_cq_idr_lock);
+                        read_unlock(&ehca_cq_idr_lock);
                         if (!eqe_cache[eqe_cnt].cq) {
                                 ehca_err(&shca->ib_device,
                                          "Invalid eqe for non-existing cq "
diff --git a/drivers/infiniband/hw/ehca/ehca_main.c b/drivers/infiniband/hw/ehca/ehca_main.c
index 32396b203f14..28ba2dd24216 100644
--- a/drivers/infiniband/hw/ehca/ehca_main.c
+++ b/drivers/infiniband/hw/ehca/ehca_main.c
@@ -96,8 +96,8 @@ MODULE_PARM_DESC(static_rate,
 MODULE_PARM_DESC(scaling_code,
                  "set scaling code (0: disabled/default, 1: enabled)");
 
-DEFINE_SPINLOCK(ehca_qp_idr_lock);
-DEFINE_SPINLOCK(ehca_cq_idr_lock);
+DEFINE_RWLOCK(ehca_qp_idr_lock);
+DEFINE_RWLOCK(ehca_cq_idr_lock);
 DEFINE_IDR(ehca_qp_idr);
 DEFINE_IDR(ehca_cq_idr);
 
diff --git a/drivers/infiniband/hw/ehca/ehca_qp.c b/drivers/infiniband/hw/ehca/ehca_qp.c
index 31d21526df5e..74671250303f 100644
--- a/drivers/infiniband/hw/ehca/ehca_qp.c
+++ b/drivers/infiniband/hw/ehca/ehca_qp.c
@@ -512,9 +512,9 @@ struct ehca_qp *internal_create_qp(struct ib_pd *pd,
                         goto create_qp_exit0;
                 }
 
-                spin_lock_irqsave(&ehca_qp_idr_lock, flags);
+                write_lock_irqsave(&ehca_qp_idr_lock, flags);
                 ret = idr_get_new(&ehca_qp_idr, my_qp, &my_qp->token);
-                spin_unlock_irqrestore(&ehca_qp_idr_lock, flags);
+                write_unlock_irqrestore(&ehca_qp_idr_lock, flags);
 
         } while (ret == -EAGAIN);
 
@@ -733,9 +733,9 @@ create_qp_exit2:
         hipz_h_destroy_qp(shca->ipz_hca_handle, my_qp);
 
 create_qp_exit1:
-        spin_lock_irqsave(&ehca_qp_idr_lock, flags);
+        write_lock_irqsave(&ehca_qp_idr_lock, flags);
         idr_remove(&ehca_qp_idr, my_qp->token);
-        spin_unlock_irqrestore(&ehca_qp_idr_lock, flags);
+        write_unlock_irqrestore(&ehca_qp_idr_lock, flags);
 
 create_qp_exit0:
         kmem_cache_free(qp_cache, my_qp);
@@ -1706,9 +1706,9 @@ int internal_destroy_qp(struct ib_device *dev, struct ehca_qp *my_qp,
                 }
         }
 
-        spin_lock_irqsave(&ehca_qp_idr_lock, flags);
+        write_lock_irqsave(&ehca_qp_idr_lock, flags);
         idr_remove(&ehca_qp_idr, my_qp->token);
-        spin_unlock_irqrestore(&ehca_qp_idr_lock, flags);
+        write_unlock_irqrestore(&ehca_qp_idr_lock, flags);
 
         h_ret = hipz_h_destroy_qp(shca->ipz_hca_handle, my_qp);
         if (h_ret != H_SUCCESS) {
diff --git a/drivers/infiniband/hw/ehca/ehca_uverbs.c b/drivers/infiniband/hw/ehca/ehca_uverbs.c
index d8fe37d56f1a..3031b3bb56f9 100644
--- a/drivers/infiniband/hw/ehca/ehca_uverbs.c
+++ b/drivers/infiniband/hw/ehca/ehca_uverbs.c
@@ -253,7 +253,6 @@ int ehca_mmap(struct ib_ucontext *context, struct vm_area_struct *vma)
         u32 rsrc_type = (fileoffset >> 24) & 0xF; /* sq,rq,cmnd_window */
         u32 cur_pid = current->tgid;
         u32 ret;
-        unsigned long flags;
         struct ehca_cq *cq;
         struct ehca_qp *qp;
         struct ehca_pd *pd;
@@ -261,9 +260,9 @@ int ehca_mmap(struct ib_ucontext *context, struct vm_area_struct *vma)
 
         switch (q_type) {
         case  1: /* CQ */
-                spin_lock_irqsave(&ehca_cq_idr_lock, flags);
+                read_lock(&ehca_cq_idr_lock);
                 cq = idr_find(&ehca_cq_idr, idr_handle);
-                spin_unlock_irqrestore(&ehca_cq_idr_lock, flags);
+                read_unlock(&ehca_cq_idr_lock);
 
                 /* make sure this mmap really belongs to the authorized user */
                 if (!cq)
@@ -289,9 +288,9 @@ int ehca_mmap(struct ib_ucontext *context, struct vm_area_struct *vma)
                 break;
 
         case 2: /* QP */
-                spin_lock_irqsave(&ehca_qp_idr_lock, flags);
+                read_lock(&ehca_qp_idr_lock);
                 qp = idr_find(&ehca_qp_idr, idr_handle);
-                spin_unlock_irqrestore(&ehca_qp_idr_lock, flags);
+                read_unlock(&ehca_qp_idr_lock);
 
                 /* make sure this mmap really belongs to the authorized user */
                 if (!qp)