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authorJaroslav Kysela <perex@perex.cz>2010-01-27 12:10:13 -0500
committerJaroslav Kysela <perex@perex.cz>2010-01-27 12:17:27 -0500
commit7910b4a1db63fefc3d291853d33c34c5b6352e8e (patch)
treee68f8581906f00f4cdefa2f1017555dd9fdb4d74 /sound/core
parente7636925789b042ff9d98c51d48392e8c5549480 (diff)
ALSA: pcm_native - fix runtime->boundary calculation
The code in pcm_lib updating runtime->hw_ptr_interrupt expects that runtime->boundary is divisible with runtime->period_size. Thanks are going to Clemens Ladisch for the notice. Fix the runtime->boundary calculation using buffer_size * period_size as base and find a least common multiple for 32bit platforms when the expression might overflow. Signed-off-by: Jaroslav Kysela <perex@perex.cz>
Diffstat (limited to 'sound/core')
-rw-r--r--sound/core/pcm_native.c39
1 files changed, 36 insertions, 3 deletions
diff --git a/sound/core/pcm_native.c b/sound/core/pcm_native.c
index 7a002db512b4..9cbaf90d3d88 100644
--- a/sound/core/pcm_native.c
+++ b/sound/core/pcm_native.c
@@ -27,6 +27,7 @@
27#include <linux/pm_qos_params.h> 27#include <linux/pm_qos_params.h>
28#include <linux/uio.h> 28#include <linux/uio.h>
29#include <linux/dma-mapping.h> 29#include <linux/dma-mapping.h>
30#include <linux/math64.h>
30#include <sound/core.h> 31#include <sound/core.h>
31#include <sound/control.h> 32#include <sound/control.h>
32#include <sound/info.h> 33#include <sound/info.h>
@@ -366,6 +367,38 @@ static int period_to_usecs(struct snd_pcm_runtime *runtime)
366 return usecs; 367 return usecs;
367} 368}
368 369
370static int calc_boundary(struct snd_pcm_runtime *runtime)
371{
372 u_int64_t boundary;
373
374 boundary = (u_int64_t)runtime->buffer_size *
375 (u_int64_t)runtime->period_size;
376#if BITS_PER_LONG < 64
377 /* try to find lowest common multiple for buffer and period */
378 if (boundary > LONG_MAX - runtime->buffer_size) {
379 u_int32_t remainder = -1;
380 u_int32_t divident = runtime->buffer_size;
381 u_int32_t divisor = runtime->period_size;
382 while (remainder) {
383 remainder = divident % divisor;
384 if (remainder) {
385 divident = divisor;
386 divisor = remainder;
387 }
388 }
389 boundary = div_u64(boundary, divisor);
390 if (boundary > LONG_MAX - runtime->buffer_size)
391 return -ERANGE;
392 }
393#endif
394 if (boundary == 0)
395 return -ERANGE;
396 runtime->boundary = boundary;
397 while (runtime->boundary * 2 <= LONG_MAX - runtime->buffer_size)
398 runtime->boundary *= 2;
399 return 0;
400}
401
369static int snd_pcm_hw_params(struct snd_pcm_substream *substream, 402static int snd_pcm_hw_params(struct snd_pcm_substream *substream,
370 struct snd_pcm_hw_params *params) 403 struct snd_pcm_hw_params *params)
371{ 404{
@@ -441,9 +474,9 @@ static int snd_pcm_hw_params(struct snd_pcm_substream *substream,
441 runtime->stop_threshold = runtime->buffer_size; 474 runtime->stop_threshold = runtime->buffer_size;
442 runtime->silence_threshold = 0; 475 runtime->silence_threshold = 0;
443 runtime->silence_size = 0; 476 runtime->silence_size = 0;
444 runtime->boundary = runtime->buffer_size; 477 err = calc_boundary(runtime);
445 while (runtime->boundary * 2 <= LONG_MAX - runtime->buffer_size) 478 if (err < 0)
446 runtime->boundary *= 2; 479 goto _error;
447 480
448 snd_pcm_timer_resolution_change(substream); 481 snd_pcm_timer_resolution_change(substream);
449 runtime->status->state = SNDRV_PCM_STATE_SETUP; 482 runtime->status->state = SNDRV_PCM_STATE_SETUP;