From: Takashi Iwai Date: Tue, 14 Nov 2006 12:03:19 +0000 (+0100) Subject: [ALSA] Fix races in PCM OSS emulation X-Git-Tag: v2.6.20-rc2~86^2~10 X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=e3a5d59a17e9a42e3f3e0e37342b2679bab2ff43;p=linux-2.6 [ALSA] Fix races in PCM OSS emulation Fixed the race among multiple threads accessing the OSS PCM instance concurrently by simply introducing a mutex for protecting a setup of the PCM. Signed-off-by: Takashi Iwai Signed-off-by: Jaroslav Kysela --- diff --git a/include/sound/pcm_oss.h b/include/sound/pcm_oss.h index c854647b6f..1cd4f64cdf 100644 --- a/include/sound/pcm_oss.h +++ b/include/sound/pcm_oss.h @@ -56,6 +56,7 @@ struct snd_pcm_oss_runtime { size_t mmap_bytes; char *buffer; /* vmallocated period */ size_t buffer_used; /* used length from period buffer */ + struct mutex params_lock; #ifdef CONFIG_SND_PCM_OSS_PLUGINS struct snd_pcm_plugin *plugin_first; struct snd_pcm_plugin *plugin_last; diff --git a/sound/core/oss/pcm_oss.c b/sound/core/oss/pcm_oss.c index e0821eb3d8..786a82e688 100644 --- a/sound/core/oss/pcm_oss.c +++ b/sound/core/oss/pcm_oss.c @@ -810,6 +810,8 @@ static int snd_pcm_oss_change_params(struct snd_pcm_substream *substream) struct snd_mask sformat_mask; struct snd_mask mask; + if (mutex_lock_interruptible(&runtime->oss.params_lock)) + return -EINTR; sw_params = kmalloc(sizeof(*sw_params), GFP_KERNEL); params = kmalloc(sizeof(*params), GFP_KERNEL); sparams = kmalloc(sizeof(*sparams), GFP_KERNEL); @@ -1020,6 +1022,7 @@ failure: kfree(sw_params); kfree(params); kfree(sparams); + mutex_unlock(&runtime->oss.params_lock); return err; } @@ -1307,14 +1310,17 @@ static ssize_t snd_pcm_oss_write1(struct snd_pcm_substream *substream, const cha if ((tmp = snd_pcm_oss_make_ready(substream)) < 0) return tmp; + mutex_lock(&runtime->oss.params_lock); while (bytes > 0) { if (bytes < runtime->oss.period_bytes || runtime->oss.buffer_used > 0) { tmp = bytes; if (tmp + runtime->oss.buffer_used > runtime->oss.period_bytes) tmp = runtime->oss.period_bytes - runtime->oss.buffer_used; if (tmp > 0) { - if (copy_from_user(runtime->oss.buffer + runtime->oss.buffer_used, buf, tmp)) - return xfer > 0 ? (snd_pcm_sframes_t)xfer : -EFAULT; + if (copy_from_user(runtime->oss.buffer + runtime->oss.buffer_used, buf, tmp)) { + tmp = -EFAULT; + goto err; + } } runtime->oss.buffer_used += tmp; buf += tmp; @@ -1325,22 +1331,24 @@ static ssize_t snd_pcm_oss_write1(struct snd_pcm_substream *substream, const cha tmp = snd_pcm_oss_write2(substream, runtime->oss.buffer + runtime->oss.period_ptr, runtime->oss.buffer_used - runtime->oss.period_ptr, 1); if (tmp <= 0) - return xfer > 0 ? (snd_pcm_sframes_t)xfer : tmp; + goto err; runtime->oss.bytes += tmp; runtime->oss.period_ptr += tmp; runtime->oss.period_ptr %= runtime->oss.period_bytes; if (runtime->oss.period_ptr == 0 || runtime->oss.period_ptr == runtime->oss.buffer_used) runtime->oss.buffer_used = 0; - else if ((substream->f_flags & O_NONBLOCK) != 0) - return xfer > 0 ? xfer : -EAGAIN; + else if ((substream->f_flags & O_NONBLOCK) != 0) { + tmp = -EAGAIN; + goto err; + } } } else { tmp = snd_pcm_oss_write2(substream, (const char __force *)buf, runtime->oss.period_bytes, 0); if (tmp <= 0) - return xfer > 0 ? (snd_pcm_sframes_t)xfer : tmp; + goto err; runtime->oss.bytes += tmp; buf += tmp; bytes -= tmp; @@ -1350,7 +1358,12 @@ static ssize_t snd_pcm_oss_write1(struct snd_pcm_substream *substream, const cha break; } } + mutex_unlock(&runtime->oss.params_lock); return xfer; + + err: + mutex_unlock(&runtime->oss.params_lock); + return xfer > 0 ? (snd_pcm_sframes_t)xfer : tmp; } static ssize_t snd_pcm_oss_read2(struct snd_pcm_substream *substream, char *buf, size_t bytes, int in_kernel) @@ -1397,12 +1410,13 @@ static ssize_t snd_pcm_oss_read1(struct snd_pcm_substream *substream, char __use if ((tmp = snd_pcm_oss_make_ready(substream)) < 0) return tmp; + mutex_lock(&runtime->oss.params_lock); while (bytes > 0) { if (bytes < runtime->oss.period_bytes || runtime->oss.buffer_used > 0) { if (runtime->oss.buffer_used == 0) { tmp = snd_pcm_oss_read2(substream, runtime->oss.buffer, runtime->oss.period_bytes, 1); if (tmp <= 0) - return xfer > 0 ? (snd_pcm_sframes_t)xfer : tmp; + goto err; runtime->oss.bytes += tmp; runtime->oss.period_ptr = tmp; runtime->oss.buffer_used = tmp; @@ -1410,8 +1424,10 @@ static ssize_t snd_pcm_oss_read1(struct snd_pcm_substream *substream, char __use tmp = bytes; if ((size_t) tmp > runtime->oss.buffer_used) tmp = runtime->oss.buffer_used; - if (copy_to_user(buf, runtime->oss.buffer + (runtime->oss.period_ptr - runtime->oss.buffer_used), tmp)) - return xfer > 0 ? (snd_pcm_sframes_t)xfer : -EFAULT; + if (copy_to_user(buf, runtime->oss.buffer + (runtime->oss.period_ptr - runtime->oss.buffer_used), tmp)) { + tmp = -EFAULT; + goto err; + } buf += tmp; bytes -= tmp; xfer += tmp; @@ -1420,14 +1436,19 @@ static ssize_t snd_pcm_oss_read1(struct snd_pcm_substream *substream, char __use tmp = snd_pcm_oss_read2(substream, (char __force *)buf, runtime->oss.period_bytes, 0); if (tmp <= 0) - return xfer > 0 ? (snd_pcm_sframes_t)xfer : tmp; + goto err; runtime->oss.bytes += tmp; buf += tmp; bytes -= tmp; xfer += tmp; } } + mutex_unlock(&runtime->oss.params_lock); return xfer; + + err: + mutex_unlock(&runtime->oss.params_lock); + return xfer > 0 ? (snd_pcm_sframes_t)xfer : tmp; } static int snd_pcm_oss_reset(struct snd_pcm_oss_file *pcm_oss_file) @@ -1528,6 +1549,7 @@ static int snd_pcm_oss_sync(struct snd_pcm_oss_file *pcm_oss_file) return err; format = snd_pcm_oss_format_from(runtime->oss.format); width = snd_pcm_format_physical_width(format); + mutex_lock(&runtime->oss.params_lock); if (runtime->oss.buffer_used > 0) { #ifdef OSS_DEBUG printk("sync: buffer_used\n"); @@ -1537,8 +1559,10 @@ static int snd_pcm_oss_sync(struct snd_pcm_oss_file *pcm_oss_file) runtime->oss.buffer + runtime->oss.buffer_used, size); err = snd_pcm_oss_sync1(substream, runtime->oss.period_bytes); - if (err < 0) + if (err < 0) { + mutex_unlock(&runtime->oss.params_lock); return err; + } } else if (runtime->oss.period_ptr > 0) { #ifdef OSS_DEBUG printk("sync: period_ptr\n"); @@ -1548,8 +1572,10 @@ static int snd_pcm_oss_sync(struct snd_pcm_oss_file *pcm_oss_file) runtime->oss.buffer, size * 8 / width); err = snd_pcm_oss_sync1(substream, size); - if (err < 0) + if (err < 0) { + mutex_unlock(&runtime->oss.params_lock); return err; + } } /* * The ALSA's period might be a bit large than OSS one. @@ -1579,6 +1605,7 @@ static int snd_pcm_oss_sync(struct snd_pcm_oss_file *pcm_oss_file) snd_pcm_lib_writev(substream, buffers, size); } } + mutex_unlock(&runtime->oss.params_lock); /* * finish sync: drain the buffer */ @@ -2172,6 +2199,7 @@ static void snd_pcm_oss_init_substream(struct snd_pcm_substream *substream, runtime->oss.params = 1; runtime->oss.trigger = 1; runtime->oss.rate = 8000; + mutex_init(&runtime->oss.params_lock); switch (SNDRV_MINOR_OSS_DEVICE(minor)) { case SNDRV_MINOR_OSS_PCM_8: runtime->oss.format = AFMT_U8;