[alsa-devel] [PATCH RFC 09/26] ALSA: pcm: Remove set_fs() in PCM core code
Takashi Iwai
tiwai at suse.de
Thu May 11 23:09:08 CEST 2017
PCM core code has a few usages of set_fs(), mostly for two purposes:
- The DELAY ioctl call from pcm_compat.c
- The ioctl wrapper in kernel context for PCM OSS and other
This patch removes the set_fs() usage in these places by a slight code
refactoring. For the former point, snd_pcm_delay() is changed to
return the value directly instead of putting the value to the given
address. The each caller stores the result in an appropriate manner.
For fixing the latter, snd_pcm_lib_kernel_ioctl() is changed to call
the functions directly as well. Now it accepts now only the limited
set of ioctls: primarily it's used by PCM OSS layer, and the only
other user is USB UAC1 gadget driver, where both drivers don't need
the full set of ioctls.
Signed-off-by: Takashi Iwai <tiwai at suse.de>
---
sound/core/pcm_compat.c | 12 ++----
sound/core/pcm_native.c | 102 ++++++++++++++++++++++++++++++------------------
2 files changed, 67 insertions(+), 47 deletions(-)
diff --git a/sound/core/pcm_compat.c b/sound/core/pcm_compat.c
index 1f64ab0c2a95..8a0f8d51e95d 100644
--- a/sound/core/pcm_compat.c
+++ b/sound/core/pcm_compat.c
@@ -27,17 +27,13 @@ static int snd_pcm_ioctl_delay_compat(struct snd_pcm_substream *substream,
s32 __user *src)
{
snd_pcm_sframes_t delay;
- mm_segment_t fs;
- int err;
- fs = snd_enter_user();
- err = snd_pcm_delay(substream, &delay);
- snd_leave_user(fs);
- if (err < 0)
- return err;
+ delay = snd_pcm_delay(substream);
+ if (delay < 0)
+ return delay;
if (put_user(delay, src))
return -EFAULT;
- return err;
+ return 0;
}
static int snd_pcm_ioctl_rewind_compat(struct snd_pcm_substream *substream,
diff --git a/sound/core/pcm_native.c b/sound/core/pcm_native.c
index 13dec5ec93f2..f9bd56958cad 100644
--- a/sound/core/pcm_native.c
+++ b/sound/core/pcm_native.c
@@ -181,20 +181,6 @@ void snd_pcm_stream_unlock_irqrestore(struct snd_pcm_substream *substream,
}
EXPORT_SYMBOL_GPL(snd_pcm_stream_unlock_irqrestore);
-static inline mm_segment_t snd_enter_user(void)
-{
- mm_segment_t fs = get_fs();
- set_fs(get_ds());
- return fs;
-}
-
-static inline void snd_leave_user(mm_segment_t fs)
-{
- set_fs(fs);
-}
-
-
-
int snd_pcm_info(struct snd_pcm_substream *substream, struct snd_pcm_info *info)
{
struct snd_pcm_runtime *runtime;
@@ -1081,6 +1067,7 @@ static const struct action_ops snd_pcm_action_start = {
* @substream: the PCM substream instance
*
* Return: Zero if successful, or a negative error code.
+ * The stream lock must be acquired before calling this function.
*/
int snd_pcm_start(struct snd_pcm_substream *substream)
{
@@ -1088,6 +1075,13 @@ int snd_pcm_start(struct snd_pcm_substream *substream)
SNDRV_PCM_STATE_RUNNING);
}
+/* take the stream lock and start the streams */
+static int snd_pcm_start_lock_irq(struct snd_pcm_substream *substream)
+{
+ return snd_pcm_action_lock_irq(&snd_pcm_action_start, substream,
+ SNDRV_PCM_STATE_RUNNING);
+}
+
/*
* stop callbacks
*/
@@ -2655,8 +2649,7 @@ static int snd_pcm_hwsync(struct snd_pcm_substream *substream)
return err;
}
-static int snd_pcm_delay(struct snd_pcm_substream *substream,
- snd_pcm_sframes_t __user *res)
+static snd_pcm_sframes_t snd_pcm_delay(struct snd_pcm_substream *substream)
{
struct snd_pcm_runtime *runtime = substream->runtime;
int err;
@@ -2690,10 +2683,7 @@ static int snd_pcm_delay(struct snd_pcm_substream *substream,
break;
}
snd_pcm_stream_unlock_irq(substream);
- if (!err)
- if (put_user(n, res))
- err = -EFAULT;
- return err;
+ return err < 0 ? err : n;
}
static int snd_pcm_sync_ptr(struct snd_pcm_substream *substream,
@@ -2781,7 +2771,7 @@ static int snd_pcm_common_ioctl1(struct file *file,
case SNDRV_PCM_IOCTL_RESET:
return snd_pcm_reset(substream);
case SNDRV_PCM_IOCTL_START:
- return snd_pcm_action_lock_irq(&snd_pcm_action_start, substream, SNDRV_PCM_STATE_RUNNING);
+ return snd_pcm_start_lock_irq(substream);
case SNDRV_PCM_IOCTL_LINK:
return snd_pcm_link(substream, (int)(unsigned long) arg);
case SNDRV_PCM_IOCTL_UNLINK:
@@ -2793,7 +2783,16 @@ static int snd_pcm_common_ioctl1(struct file *file,
case SNDRV_PCM_IOCTL_HWSYNC:
return snd_pcm_hwsync(substream);
case SNDRV_PCM_IOCTL_DELAY:
- return snd_pcm_delay(substream, arg);
+ {
+ snd_pcm_sframes_t delay = snd_pcm_delay(substream);
+ snd_pcm_sframes_t __user *res = arg;
+
+ if (delay < 0)
+ return delay;
+ if (put_user(delay, res))
+ return -EFAULT;
+ return 0;
+ }
case SNDRV_PCM_IOCTL_SYNC_PTR:
return snd_pcm_sync_ptr(substream, arg);
#ifdef CONFIG_SND_SUPPORT_OLD_API
@@ -3007,30 +3006,55 @@ static long snd_pcm_capture_ioctl(struct file *file, unsigned int cmd,
(void __user *)arg);
}
+/**
+ * snd_pcm_kernel_ioctl - Execute PCM ioctl in the kernel-space
+ * @substream: PCM substream
+ * @cmd: IOCTL cmd
+ * @arg: IOCTL argument
+ *
+ * The function is provided primarily for OSS layer and USB gadget drivers,
+ * and it allows only the limited set of ioctls (hw_params, sw_params,
+ * prepare, start, drain, drop, forward).
+ */
int snd_pcm_kernel_ioctl(struct snd_pcm_substream *substream,
unsigned int cmd, void *arg)
{
- mm_segment_t fs;
- int result;
+ snd_pcm_uframes_t *frames = arg;
+ snd_pcm_sframes_t result;
- fs = snd_enter_user();
- switch (substream->stream) {
- case SNDRV_PCM_STREAM_PLAYBACK:
- result = snd_pcm_playback_ioctl1(NULL, substream, cmd,
- (void __user *)arg);
- break;
- case SNDRV_PCM_STREAM_CAPTURE:
- result = snd_pcm_capture_ioctl1(NULL, substream, cmd,
- (void __user *)arg);
- break;
+ switch (cmd) {
+ case SNDRV_PCM_IOCTL_FORWARD:
+ {
+ /* provided only for OSS; capture-only and no value returned */
+ if (substream->stream != SNDRV_PCM_STREAM_CAPTURE)
+ return -EINVAL;
+ result = snd_pcm_capture_forward(substream, *frames);
+ return result < 0 ? result : 0;
+ }
+ case SNDRV_PCM_IOCTL_HW_PARAMS:
+ return snd_pcm_hw_params(substream, arg);
+ case SNDRV_PCM_IOCTL_SW_PARAMS:
+ return snd_pcm_sw_params(substream, arg);
+ case SNDRV_PCM_IOCTL_PREPARE:
+ return snd_pcm_prepare(substream, NULL);
+ case SNDRV_PCM_IOCTL_START:
+ return snd_pcm_start_lock_irq(substream);
+ case SNDRV_PCM_IOCTL_DRAIN:
+ return snd_pcm_drain(substream, NULL);
+ case SNDRV_PCM_IOCTL_DROP:
+ return snd_pcm_drop(substream);
+ case SNDRV_PCM_IOCTL_DELAY:
+ {
+ result = snd_pcm_delay(substream);
+ if (result < 0)
+ return result;
+ *frames = result;
+ return 0;
+ }
default:
- result = -EINVAL;
- break;
+ return -EINVAL;
}
- snd_leave_user(fs);
- return result;
}
-
EXPORT_SYMBOL(snd_pcm_kernel_ioctl);
static ssize_t snd_pcm_read(struct file *file, char __user *buf, size_t count,
--
2.12.2
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