[MIPS] RTLX, VPE: Make open actually atomic.

Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

2 files changed, 23 insertions, 28 deletions

diff --git a/arch/mips/kernel/rtlx.c b/arch/mips/kernel/rtlx.c
index 766db51ab69e..7a8683ab6fde 100644
--- a/arch/mips/kernel/rtlx.c
+++ b/arch/mips/kernel/rtlx.c
@@ -53,7 +53,7 @@ static char module_name[] = "rtlx";
 static struct chan_waitqueues {
         wait_queue_head_t rt_queue;
         wait_queue_head_t lx_queue;
-        int in_open;
+        atomic_t in_open;
 } channel_wqs[RTLX_CHANNELS];
 
 static struct irqaction irq;
@@ -148,6 +148,7 @@ int rtlx_open(int index, int can_sleep)
 {
         volatile struct rtlx_info **p;
         struct rtlx_channel *chan;
+        enum rtlx_state state;
         int ret = 0;
 
         if (index >= RTLX_CHANNELS) {
@@ -155,13 +156,13 @@ int rtlx_open(int index, int can_sleep)
                 return -ENOSYS;
         }
 
-        if (channel_wqs[index].in_open) {
-                printk(KERN_DEBUG "rtlx_open channel %d already opened\n", index);
-                return -EBUSY;
+        if (atomic_inc_return(&channel_wqs[index].in_open) > 1) {
+                printk(KERN_DEBUG "rtlx_open channel %d already opened\n",
+                       index);
+                ret = -EBUSY;
+                goto out_fail;
         }
 
-        channel_wqs[index].in_open++;
-
         if (rtlx == NULL) {
                 if( (p = vpe_get_shared(RTLX_TARG_VPE)) == NULL) {
                         if (can_sleep) {
@@ -173,9 +174,8 @@ int rtlx_open(int index, int can_sleep)
                                 if (ret)
                                         goto out_fail;
                         } else {
-                                printk( KERN_DEBUG "No SP program loaded, and device "
+                                printk(KERN_DEBUG "No SP program loaded, and device "
                                         "opened with O_NONBLOCK\n");
-                                channel_wqs[index].in_open = 0;
                                 ret = -ENOSYS;
                                 goto out_fail;
                         }
@@ -193,7 +193,6 @@ int rtlx_open(int index, int can_sleep)
                         } else {
                                 printk(" *vpe_get_shared is NULL. "
                                        "Has an SP program been loaded?\n");
-                                channel_wqs[index].in_open = 0;
                                 ret = -ENOSYS;
                                 goto out_fail;
                         }
@@ -202,31 +201,28 @@ int rtlx_open(int index, int can_sleep)
                 if ((unsigned int)*p < KSEG0) {
                         printk(KERN_WARNING "vpe_get_shared returned an invalid pointer "
                                "maybe an error code %d\n", (int)*p);
-                        channel_wqs[index].in_open = 0;
                         ret = -ENOSYS;
                         goto out_fail;
                 }
 
-                if ((ret = rtlx_init(*p)) < 0) {
-                        channel_wqs[index].in_open = 0;
-                        return ret;
-                }
+                if ((ret = rtlx_init(*p)) < 0)
+                        goto out_ret;
         }
 
         chan = &rtlx->channel[index];
 
-        if (chan->lx_state == RTLX_STATE_OPENED) {
-                channel_wqs[index].in_open = 0;
-                return -EBUSY;
-        }
-
-        chan->lx_state = RTLX_STATE_OPENED;
-        channel_wqs[index].in_open = 0;
-        return 0;
+        state = xchg(&chan->lx_state, RTLX_STATE_OPENED);
+        if (state == RTLX_STATE_OPENED) {
+                ret = -EBUSY;
+                goto out_fail;
+        }
 
 out_fail:
-        channel_wqs[index].in_open--;
+        smp_mb();
+        atomic_dec(&channel_wqs[index].in_open);
+        smp_mb();
 
+out_ret:
         return ret;
 }
 
@@ -475,7 +471,7 @@ static int rtlx_module_init(void)
         for (i = 0; i < RTLX_CHANNELS; i++) {
                 init_waitqueue_head(&channel_wqs[i].rt_queue);
                 init_waitqueue_head(&channel_wqs[i].lx_queue);
-                channel_wqs[i].in_open = 0;
+                atomic_set(&channel_wqs[i].in_open, 0);
 
                 dev = device_create(mt_class, NULL, MKDEV(major, i),
                                     "%s%d", module_name, i);
diff --git a/arch/mips/kernel/vpe.c b/arch/mips/kernel/vpe.c
index 9aca871a307f..c9ee9d2d5856 100644
--- a/arch/mips/kernel/vpe.c
+++ b/arch/mips/kernel/vpe.c
@@ -1079,6 +1079,7 @@ static int getcwd(char *buff, int size)
 static int vpe_open(struct inode *inode, struct file *filp)
 {
         int minor, ret;
+        enum vpe_state state;
         struct vpe *v;
         struct vpe_notifications *not;
 
@@ -1093,7 +1094,8 @@ static int vpe_open(struct inode *inode, struct file *filp)
                 return -ENODEV;
         }
 
-        if (v->state != VPE_STATE_UNUSED) {
+        state = xchg(&v->state, VPE_STATE_INUSE);
+        if (state != VPE_STATE_UNUSED) {
                 dvpe();
 
                 printk(KERN_DEBUG "VPE loader: tc in use dumping regs\n");
@@ -1108,9 +1110,6 @@ static int vpe_open(struct inode *inode, struct file *filp)
                 cleanup_tc(get_tc(minor));
         }
 
-        // allocate it so when we get write ops we know it's expected.
-        v->state = VPE_STATE_INUSE;
-
         /* this of-course trashes what was there before... */
         v->pbuffer = vmalloc(P_SIZE);
         v->plen = P_SIZE;