mg_disk: fix locking

IRQ and timeout handlers call functions which expect locked queue lock
without locking it.  Fix it.

While at it, convert 0s used as null pointer constant to NULLs.

[ Impact: fix locking, cleanup ]

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: unsik Kim <donari75@gmail.com>

1 files changed, 13 insertions, 4 deletions

diff --git a/drivers/block/mg_disk.c b/drivers/block/mg_disk.c
index fb39d9aa3cdc..d3e72ad08dbe 100644
--- a/drivers/block/mg_disk.c
+++ b/drivers/block/mg_disk.c
@@ -160,11 +160,16 @@ static irqreturn_t mg_irq(int irq, void *dev_id)
         struct mg_host *host = dev_id;
         void (*handler)(struct mg_host *) = host->mg_do_intr;
 
-        host->mg_do_intr = 0;
+        spin_lock(&host->lock);
+
+        host->mg_do_intr = NULL;
         del_timer(&host->timer);
         if (!handler)
                 handler = mg_unexpected_intr;
         handler(host);
+
+        spin_unlock(&host->lock);
+
         return IRQ_HANDLED;
 }
 
@@ -319,7 +324,7 @@ static void mg_read(struct request *req)
 
         remains = req->nr_sectors;
 
-        if (mg_out(host, req->sector, req->nr_sectors, MG_CMD_RD, 0) !=
+        if (mg_out(host, req->sector, req->nr_sectors, MG_CMD_RD, NULL) !=
                         MG_ERR_NONE)
                 mg_bad_rw_intr(host);
 
@@ -363,7 +368,7 @@ static void mg_write(struct request *req)
 
         remains = req->nr_sectors;
 
-        if (mg_out(host, req->sector, req->nr_sectors, MG_CMD_WR, 0) !=
+        if (mg_out(host, req->sector, req->nr_sectors, MG_CMD_WR, NULL) !=
                         MG_ERR_NONE) {
                 mg_bad_rw_intr(host);
                 return;
@@ -521,9 +526,11 @@ void mg_times_out(unsigned long data)
         char *name;
         struct request *req;
 
+        spin_lock_irq(&host->lock);
+
         req = elv_next_request(host->breq);
         if (!req)
-                return;
+                goto out_unlock;
 
         host->mg_do_intr = NULL;
 
@@ -534,6 +541,8 @@ void mg_times_out(unsigned long data)
         mg_bad_rw_intr(host);
 
         mg_request(host->breq);
+out_unlock:
+        spin_unlock_irq(&host->lock);
 }
 
 static void mg_request_poll(struct request_queue *q)