diff options
author | André Fabian Silva Delgado <emulatorman@parabola.nu> | 2016-03-25 03:53:42 -0300 |
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committer | André Fabian Silva Delgado <emulatorman@parabola.nu> | 2016-03-25 03:53:42 -0300 |
commit | 03dd4cb26d967f9588437b0fc9cc0e8353322bb7 (patch) | |
tree | fa581f6dc1c0596391690d1f67eceef3af8246dc /drivers/staging/comedi/comedi_fops.c | |
parent | d4e493caf788ef44982e131ff9c786546904d934 (diff) |
Linux-libre 4.5-gnu
Diffstat (limited to 'drivers/staging/comedi/comedi_fops.c')
-rw-r--r-- | drivers/staging/comedi/comedi_fops.c | 124 |
1 files changed, 56 insertions, 68 deletions
diff --git a/drivers/staging/comedi/comedi_fops.c b/drivers/staging/comedi/comedi_fops.c index 7b4af519e..d57fadef4 100644 --- a/drivers/staging/comedi/comedi_fops.c +++ b/drivers/staging/comedi/comedi_fops.c @@ -2303,11 +2303,13 @@ static ssize_t comedi_write(struct file *file, const char __user *buf, { struct comedi_subdevice *s; struct comedi_async *async; - int n, m, count = 0, retval = 0; + unsigned int n, m; + ssize_t count = 0; + int retval = 0; DECLARE_WAITQUEUE(wait, current); struct comedi_file *cfp = file->private_data; struct comedi_device *dev = cfp->dev; - bool on_wait_queue = false; + bool become_nonbusy = false; bool attach_locked; unsigned int old_detach_count; @@ -2329,74 +2331,33 @@ static ssize_t comedi_write(struct file *file, const char __user *buf, } async = s->async; - - if (!s->busy || !nbytes) - goto out; - if (s->busy != file) { - retval = -EACCES; - goto out; - } - if (!(async->cmd.flags & CMDF_WRITE)) { + if (s->busy != file || !(async->cmd.flags & CMDF_WRITE)) { retval = -EINVAL; goto out; } add_wait_queue(&async->wait_head, &wait); - on_wait_queue = true; - while (nbytes > 0 && !retval) { + while (count == 0 && !retval) { unsigned runflags; + unsigned int wp, n1, n2; set_current_state(TASK_INTERRUPTIBLE); runflags = comedi_get_subdevice_runflags(s); if (!comedi_is_runflags_running(runflags)) { - if (count == 0) { - struct comedi_subdevice *new_s; - - if (comedi_is_runflags_in_error(runflags)) - retval = -EPIPE; - else - retval = 0; - /* - * To avoid deadlock, cannot acquire dev->mutex - * while dev->attach_lock is held. Need to - * remove task from the async wait queue before - * releasing dev->attach_lock, as it might not - * be valid afterwards. - */ - remove_wait_queue(&async->wait_head, &wait); - on_wait_queue = false; - up_read(&dev->attach_lock); - attach_locked = false; - mutex_lock(&dev->mutex); - /* - * Become non-busy unless things have changed - * behind our back. Checking dev->detach_count - * is unchanged ought to be sufficient (unless - * there have been 2**32 detaches in the - * meantime!), but check the subdevice pointer - * as well just in case. - */ - new_s = comedi_file_write_subdevice(file); - if (dev->attached && - old_detach_count == dev->detach_count && - s == new_s && new_s->async == async) - do_become_nonbusy(dev, s); - mutex_unlock(&dev->mutex); - } + if (comedi_is_runflags_in_error(runflags)) + retval = -EPIPE; + if (retval || nbytes) + become_nonbusy = true; break; } + if (nbytes == 0) + break; - n = nbytes; - - m = n; - if (async->buf_write_ptr + m > async->prealloc_bufsz) - m = async->prealloc_bufsz - async->buf_write_ptr; + /* Allocate all free buffer space. */ comedi_buf_write_alloc(s, async->prealloc_bufsz); - if (m > comedi_buf_write_n_allocated(s)) - m = comedi_buf_write_n_allocated(s); - if (m < n) - n = m; + m = comedi_buf_write_n_allocated(s); + n = min_t(size_t, m, nbytes); if (n == 0) { if (file->f_flags & O_NONBLOCK) { @@ -2408,21 +2369,22 @@ static ssize_t comedi_write(struct file *file, const char __user *buf, retval = -ERESTARTSYS; break; } - if (!s->busy) - break; - if (s->busy != file) { - retval = -EACCES; - break; - } - if (!(async->cmd.flags & CMDF_WRITE)) { + if (s->busy != file || + !(async->cmd.flags & CMDF_WRITE)) { retval = -EINVAL; break; } continue; } - m = copy_from_user(async->prealloc_buf + async->buf_write_ptr, - buf, n); + wp = async->buf_write_ptr; + n1 = min(n, async->prealloc_bufsz - wp); + n2 = n - n1; + m = copy_from_user(async->prealloc_buf + wp, buf, n1); + if (m) + m += n2; + else if (n2) + m = copy_from_user(async->prealloc_buf, buf + n1, n2); if (m) { n -= m; retval = -EFAULT; @@ -2433,12 +2395,38 @@ static ssize_t comedi_write(struct file *file, const char __user *buf, nbytes -= n; buf += n; - break; /* makes device work like a pipe */ } -out: - if (on_wait_queue) - remove_wait_queue(&async->wait_head, &wait); + remove_wait_queue(&async->wait_head, &wait); set_current_state(TASK_RUNNING); + if (become_nonbusy && count == 0) { + struct comedi_subdevice *new_s; + + /* + * To avoid deadlock, cannot acquire dev->mutex + * while dev->attach_lock is held. + */ + up_read(&dev->attach_lock); + attach_locked = false; + mutex_lock(&dev->mutex); + /* + * Check device hasn't become detached behind our back. + * Checking dev->detach_count is unchanged ought to be + * sufficient (unless there have been 2**32 detaches in the + * meantime!), but check the subdevice pointer as well just in + * case. + * + * Also check the subdevice is still in a suitable state to + * become non-busy in case it changed behind our back. + */ + new_s = comedi_file_write_subdevice(file); + if (dev->attached && old_detach_count == dev->detach_count && + s == new_s && new_s->async == async && s->busy == file && + (async->cmd.flags & CMDF_WRITE) && + !comedi_is_subdevice_running(s)) + do_become_nonbusy(dev, s); + mutex_unlock(&dev->mutex); + } +out: if (attach_locked) up_read(&dev->attach_lock); |