From: Eldad Zinger <eldadz@mellanox.co.il>
Date: Sun, 4 Jul 2010 13:30:43 +0000 (+0300)
Subject: sdp: device_removal_lock should not be a spinlock because module removal takes a... 
X-Git-Tag: v4.1.12-92~264^2~5^2~152
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=d88b3468e769df80bea2425d10687a37cd36a6f9;p=users%2Fjedix%2Flinux-maple.git

sdp: device_removal_lock should not be a spinlock because module removal takes a long time.

In order to prevent a situation that many CPUs are stack with read-spinlock
waiting for remove-device write-lock to be freed, I replaced the rw-spinlock
with rw-semaphore. That way the blocked processes goes to sleep and are not
blocking other processes.

Signed-off-by: Eldad Zinger <eldadz@mellanox.co.il>
---

diff --git a/drivers/infiniband/ulp/sdp/sdp.h b/drivers/infiniband/ulp/sdp/sdp.h
index fd98ca905024b..0f6babb033bda 100644
--- a/drivers/infiniband/ulp/sdp/sdp.h
+++ b/drivers/infiniband/ulp/sdp/sdp.h
@@ -3,6 +3,7 @@
 
 #include <linux/workqueue.h>
 #include <linux/wait.h>
+#include <linux/rwsem.h>
 #include <net/inet_sock.h>
 #include <net/tcp.h> /* For urgent data flags */
 #include <rdma/ib_verbs.h>
@@ -800,7 +801,7 @@ void sdp_reset_sk(struct sock *sk, int rc);
 void sdp_reset(struct sock *sk);
 int sdp_tx_wait_memory(struct sdp_sock *ssk, long *timeo_p, int *credits_needed);
 void sdp_skb_entail(struct sock *sk, struct sk_buff *skb);
-extern rwlock_t device_removal_lock;
+extern struct rw_semaphore device_removal_lock;
 
 /* sdp_proc.c */
 int __init sdp_proc_init(void);
diff --git a/drivers/infiniband/ulp/sdp/sdp_cma.c b/drivers/infiniband/ulp/sdp/sdp_cma.c
index a940579783180..35532ad00c8c8 100644
--- a/drivers/infiniband/ulp/sdp/sdp_cma.c
+++ b/drivers/infiniband/ulp/sdp/sdp_cma.c
@@ -175,18 +175,18 @@ static int sdp_connect_handler(struct sock *sk, struct rdma_cm_id *id,
 	bh_unlock_sock(child);
 	__sock_put(child, SOCK_REF_CLONE);
 
-	read_lock(&device_removal_lock);
+	down_read(&device_removal_lock);
 
 	rc = sdp_init_qp(child, id);
 	if (rc) {
-		read_unlock(&device_removal_lock);
+		up_read(&device_removal_lock);
 		sdp_sk(child)->destructed_already = 1;
 		sk_free(child);
 		return rc;
 	}
 
 	sdp_add_sock(sdp_sk(child));
-	read_unlock(&device_removal_lock);
+	up_read(&device_removal_lock);
 
 	sdp_sk(child)->max_bufs = ntohs(h->bsdh.bufs);
 	atomic_set(&sdp_sk(child)->tx_ring.credits, sdp_sk(child)->max_bufs);
diff --git a/drivers/infiniband/ulp/sdp/sdp_main.c b/drivers/infiniband/ulp/sdp/sdp_main.c
index 9acff248984eb..7c8494c3deb45 100644
--- a/drivers/infiniband/ulp/sdp/sdp_main.c
+++ b/drivers/infiniband/ulp/sdp/sdp_main.c
@@ -119,7 +119,7 @@ struct workqueue_struct *rx_comp_wq;
 struct list_head sock_list;
 spinlock_t sock_list_lock;
 
-DEFINE_RWLOCK(device_removal_lock);
+DECLARE_RWSEM(device_removal_lock);
 
 static inline unsigned int sdp_keepalive_time_when(const struct sdp_sock *ssk)
 {
@@ -521,10 +521,10 @@ static void sdp_destruct(struct sock *sk)
 
 	ssk->destructed_already = 1;
 
-	read_lock(&device_removal_lock);
+	down_read(&device_removal_lock);
 	sdp_remove_sock(ssk);
 	sdp_destroy_resources(sk);
-	read_unlock(&device_removal_lock);
+	up_read(&device_removal_lock);
 
 	flush_scheduled_work();
 
@@ -2810,7 +2810,7 @@ static void sdp_remove_device(struct ib_device *device)
 
 	/* destroy_ids: */
 do_next:
-	write_lock(&device_removal_lock);
+	down_write(&device_removal_lock);
 
 	spin_lock_irq(&sock_list_lock);
 	list_for_each_entry(ssk, &sock_list, sock_list) {
@@ -2825,7 +2825,7 @@ do_next:
 			ssk->id_destroyed_already = 1;
 
 			release_sock(sk);
-			write_unlock(&device_removal_lock);
+			up_write(&device_removal_lock);
 
 			if (id)
 				rdma_destroy_id(id);
@@ -2859,7 +2859,7 @@ kill_socks:
 
 	spin_unlock_irq(&sock_list_lock);
 
-	write_unlock(&device_removal_lock);
+	up_write(&device_removal_lock);
 
 	if (!sdp_dev)
 		return;