staging: comedi: dt282x: dt282x_ai_insn_read() always fails

[karo-tx-linux.git] / drivers / staging / comedi / comedi_fops.c

diff --git a/drivers/staging/comedi/comedi_fops.c b/drivers/staging/comedi/comedi_fops.c
index 8647518259f6dd5ab3379babc218d5ef6cf24831..34b2414e468f82cd9c5a4e60503591afecf67c02 100644 (file)
--- a/drivers/staging/comedi/comedi_fops.c
+++ b/drivers/staging/comedi/comedi_fops.c
@@ -26,7 +26,6 @@
 #include <linux/sched.h>
 #include <linux/fcntl.h>
 #include <linux/delay.h>
-#include <linux/ioport.h>
 #include <linux/mm.h>
 #include <linux/slab.h>
 #include <linux/kmod.h>
@@ -1413,22 +1412,19 @@ static int do_cmd_ioctl(struct comedi_device *dev,
                DPRINTK("subdevice busy\n");
                return -EBUSY;
        }
-       s->busy = file;
 
        /* make sure channel/gain list isn't too long */
        if (cmd.chanlist_len > s->len_chanlist) {
                DPRINTK("channel/gain list too long %u > %d\n",
                        cmd.chanlist_len, s->len_chanlist);
-               ret = -EINVAL;
-               goto cleanup;
+               return -EINVAL;
        }
 
        /* make sure channel/gain list isn't too short */
        if (cmd.chanlist_len < 1) {
                DPRINTK("channel/gain list too short %u < 1\n",
                        cmd.chanlist_len);
-               ret = -EINVAL;
-               goto cleanup;
+               return -EINVAL;
        }
 
        async->cmd = cmd;
@@ -1438,8 +1434,7 @@ static int do_cmd_ioctl(struct comedi_device *dev,
            kmalloc(async->cmd.chanlist_len * sizeof(int), GFP_KERNEL);
        if (!async->cmd.chanlist) {
                DPRINTK("allocation failed\n");
-               ret = -ENOMEM;
-               goto cleanup;
+               return -ENOMEM;
        }
 
        if (copy_from_user(async->cmd.chanlist, user_chanlist,
@@ -1491,6 +1486,9 @@ static int do_cmd_ioctl(struct comedi_device *dev,
 
        comedi_set_subdevice_runflags(s, ~0, SRF_USER | SRF_RUNNING);
 
+       /* set s->busy _after_ setting SRF_RUNNING flag to avoid race with
+        * comedi_read() or comedi_write() */
+       s->busy = file;
        ret = s->do_cmd(dev, s);
        if (ret == 0)
                return 0;
@@ -1705,6 +1703,7 @@ static int do_cancel_ioctl(struct comedi_device *dev, unsigned int arg,
                           void *file)
 {
        struct comedi_subdevice *s;
+       int ret;
 
        if (arg >= dev->n_subdevices)
                return -EINVAL;
@@ -1721,7 +1720,11 @@ static int do_cancel_ioctl(struct comedi_device *dev, unsigned int arg,
        if (s->busy != file)
                return -EBUSY;
 
-       return do_cancel(dev, s);
+       ret = do_cancel(dev, s);
+       if (comedi_get_subdevice_runflags(s) & SRF_USER)
+               wake_up_interruptible(&s->async->wait_head);
+
+       return ret;
 }
 
 /*
@@ -2053,11 +2056,13 @@ static ssize_t comedi_write(struct file *file, const char __user *buf,
 
                if (!comedi_is_subdevice_running(s)) {
                        if (count == 0) {
+                               mutex_lock(&dev->mutex);
                                if (comedi_is_subdevice_in_error(s))
                                        retval = -EPIPE;
                                else
                                        retval = 0;
                                do_become_nonbusy(dev, s);
+                               mutex_unlock(&dev->mutex);
                        }
                        break;
                }
@@ -2156,11 +2161,13 @@ static ssize_t comedi_read(struct file *file, char __user *buf, size_t nbytes,
 
                if (n == 0) {
                        if (!comedi_is_subdevice_running(s)) {
+                               mutex_lock(&dev->mutex);
                                do_become_nonbusy(dev, s);
                                if (comedi_is_subdevice_in_error(s))
                                        retval = -EPIPE;
                                else
                                        retval = 0;
+                               mutex_unlock(&dev->mutex);
                                break;
                        }
                        if (file->f_flags & O_NONBLOCK) {
@@ -2198,9 +2205,11 @@ static ssize_t comedi_read(struct file *file, char __user *buf, size_t nbytes,
                buf += n;
                break;          /* makes device work like a pipe */
        }
-       if (comedi_is_subdevice_idle(s) &&
-           async->buf_read_count - async->buf_write_count == 0) {
-               do_become_nonbusy(dev, s);
+       if (comedi_is_subdevice_idle(s)) {
+               mutex_lock(&dev->mutex);
+               if (async->buf_read_count - async->buf_write_count == 0)
+                       do_become_nonbusy(dev, s);
+               mutex_unlock(&dev->mutex);
        }
        set_current_state(TASK_RUNNING);
        remove_wait_queue(&async->wait_head, &wait);