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

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

diff --git a/arch/mips/kernel/rtlx.c b/arch/mips/kernel/rtlx.c
index 766db51..7a8683a 100644 (file)
--- 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 9aca871..c9ee9d2 100644 (file)
--- 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;