Hi,
On Jun 27 2017 17:15, Takashi Iwai wrote:
On Tue, 27 Jun 2017 10:09:37 +0200,
Takashi Sakamoto wrote:
Hi,
On Jun 27 2017 00:09, Takashi Iwai wrote:
On Sun, 25 Jun 2017 06:41:19 +0200,
Takashi Sakamoto wrote:
Handling mapping operation for status/control data includes some
supplemental operations for fallback mode. It's better to have helper
functions for this purpose.
This commit adds the helper functions.
---
src/pcm/pcm_hw.c | 48 ++++++++++++++++++++++++++++++++++--------------
1 file changed, 34 insertions(+), 14 deletions(-)
diff --git a/src/pcm/pcm_hw.c b/src/pcm/pcm_hw.c
index a648d12c..abf4afe0 100644
--- a/src/pcm/pcm_hw.c
+++ b/src/pcm/pcm_hw.c
@@ -31,6 +31,7 @@
#include <stdlib.h>
#include <stddef.h>
#include <unistd.h>
+#include <stdbool.h>
#include <signal.h>
#include <string.h>
#include <fcntl.h>
@@ -866,7 +867,7 @@ static snd_pcm_sframes_t snd_pcm_hw_readn(snd_pcm_t *pcm, void **bufs, snd_pcm_u
return xfern.result;
}
-static int snd_pcm_hw_mmap_status(snd_pcm_t *pcm)
+static int map_status_data(snd_pcm_t *pcm)
{
snd_pcm_hw_t *hw = pcm->private_data;
struct snd_pcm_sync_ptr sync_ptr;
@@ -900,7 +901,7 @@ static int snd_pcm_hw_mmap_status(snd_pcm_t *pcm)
return 0;
}
-static int snd_pcm_hw_mmap_control(snd_pcm_t *pcm)
+static int map_control_data(snd_pcm_t *pcm)
{
snd_pcm_hw_t *hw = pcm->private_data;
void *ptr;
@@ -922,10 +923,28 @@ static int snd_pcm_hw_mmap_control(snd_pcm_t *pcm)
return 0;
}
-static int snd_pcm_hw_munmap_status(snd_pcm_t *pcm)
+static int map_status_and_control_data(snd_pcm_t *pcm, bool force_fallback)
{
snd_pcm_hw_t *hw = pcm->private_data;
int err;
+
+ hw->sync_ptr_ioctl = (int)force_fallback;
+
+ err = map_status_data(pcm);
+ if (err < 0)
+ return err;
+
+ err = map_control_data(pcm);
+ if (err < 0)
+ return err;
This would leave the status mmap in the error path?
In the error path, snd_pcm_hw_open_fd() calls snd_pcm_close(), then
The status data is going to be unmapped.
snd_pcm_hw_open_fd()
->snd_pcm_close()
->snd_pcm_hw_close()
->unmap_status_and_control_data()
->unmap_status_data()
->munmap(2) or free(3)
Ah then there was already a bug there. It free/munmap unconditionally
for both status and control even for an error path of the mmap of
control (while status was mmapped).
Yep. These codes were originally written with a loose manner. But it
would be allowed because both 'mmap(NULL, non-zero)' and 'free(NULL)'
generates no error and 'sync_ptr_ioctl' works fine, and 'sync_ptr' is
assigned to NULL after deallocated.
But OK, it's no big issue and doesn't need to block the whole patchset
at this point.
For your information.
======== 8< --------
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <limits.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <sys/ioctl.h>
#include <sys/mman.h>
#include <sound/asound.h>
int main(void)
{
int fd;
size_t page_size = sysconf(_SC_PAGESIZE);
int pages;
void *status;
int status_length;
void *control;
int control_length;
fd = open("/dev/snd/pcmC0D0p", O_RDWR);
if (fd < 0) {
printf("open(2): %s\n", strerror(errno));
return EXIT_FAILURE;
}
/* Map status data. */
pages = (sizeof(struct snd_pcm_mmap_status) + page_size - 1) /
page_size;
status_length = pages * page_size;
status = MAP_FAILED;
status = mmap(NULL, status_length, PROT_READ, MAP_FILE | MAP_SHARED,
fd, SNDRV_PCM_MMAP_OFFSET_STATUS);
if (status == MAP_FAILED || status == NULL) {
close(fd);
printf("mmap(2): status: %s\n", strerror(errno));
return EXIT_FAILURE;
}
/* Map control data. */
pages = (sizeof(struct snd_pcm_mmap_control) + page_size - 1) /
page_size;
control_length = pages * page_size;
control = MAP_FAILED;
control = mmap(NULL, control_length, PROT_READ | PROT_WRITE,
MAP_FILE | MAP_SHARED, fd,
SNDRV_PCM_MMAP_OFFSET_CONTROL);
if (status == MAP_FAILED || status == NULL) {
munmap(status, status_length);
close(fd);
printf("mmap(2): control: %s\n", strerror(errno));
return EXIT_FAILURE;
}
/* Not error. */
if (munmap(NULL, 10000) < 0)
printf("unexpected: munmap(2): NULL: %s\n", strerror(errno));
/* Generate error. */
if (munmap(NULL, 0) < 0)
printf("expected: munmap(2): NULL: %s\n", strerror(errno));
/* Ditto. */
if (munmap(control, 0) < 0)
printf("expected: munmap(2): control: 0: %s\n", strerror(errno));
/* Ditto. */
if (munmap(status, 0) < 0)
printf("expected: munmap(2): status: 0: %s\n", strerror(errno));
if (munmap(control, control_length) < 0)
printf("unexpected: munmap(2): control: 0: %s\n", strerror(errno));
if (munmap(status, status_length) < 0)
printf("unexpected: munmap(2): status: 0: %s\n", strerror(errno));
close(fd);
/* Not error. */
free(NULL);
return EXIT_SUCCESS;
}
======== 8< --------
Regards
Takashi Sakamoto
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