ALSA: pcm/oss: refer to parameters instead of copying to reduce usage of kernel stack

Some functions in compatibility layer for Open Sound System interface has
local variable to copy some parameters in runtime of PCM substream, while
this can be replaced with reference of pointers to parameter itself. This
brings an advantage to reduce usage of kernel stack.

This commit applies this idea.

Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

diff --git a/sound/core/oss/pcm_oss.c b/sound/core/oss/pcm_oss.c
index 2a473513bd54bf54d2f98b2610870dda2f259598..e306f05ce51d12f1dc1a17c90a36a75ccf517d1e 100644 (file)
--- a/sound/core/oss/pcm_oss.c
+++ b/sound/core/oss/pcm_oss.c
@@ -848,7 +848,7 @@ static int snd_pcm_oss_change_params(struct snd_pcm_substream *substream,
        int direct;
        snd_pcm_format_t format, sformat;
        int n;
-       struct snd_mask sformat_mask;
+       const struct snd_mask *sformat_mask;
        struct snd_mask mask;
 
        if (trylock) {
@@ -891,18 +891,18 @@ static int snd_pcm_oss_change_params(struct snd_pcm_substream *substream,
 
        format = snd_pcm_oss_format_from(runtime->oss.format);
 
-       sformat_mask = *hw_param_mask(sparams, SNDRV_PCM_HW_PARAM_FORMAT);
+       sformat_mask = hw_param_mask_c(sparams, SNDRV_PCM_HW_PARAM_FORMAT);
        if (direct)
                sformat = format;
        else
-               sformat = snd_pcm_plug_slave_format(format, &sformat_mask);
+               sformat = snd_pcm_plug_slave_format(format, sformat_mask);
 
        if ((__force int)sformat < 0 ||
-           !snd_mask_test(&sformat_mask, (__force int)sformat)) {
+           !snd_mask_test(sformat_mask, (__force int)sformat)) {
                for (sformat = (__force snd_pcm_format_t)0;
                     (__force int)sformat <= (__force int)SNDRV_PCM_FORMAT_LAST;
                     sformat = (__force snd_pcm_format_t)((__force int)sformat + 1)) {
-                       if (snd_mask_test(&sformat_mask, (__force int)sformat) &&
+                       if (snd_mask_test(sformat_mask, (__force int)sformat) &&
                            snd_pcm_oss_format_to(sformat) >= 0)
                                break;
                }
@@ -1780,7 +1780,7 @@ static int snd_pcm_oss_get_formats(struct snd_pcm_oss_file *pcm_oss_file)
        int direct;
        struct snd_pcm_hw_params *params;
        unsigned int formats = 0;
-       struct snd_mask format_mask;
+       const struct snd_mask *format_mask;
        int fmt;
 
        if ((err = snd_pcm_oss_get_active_substream(pcm_oss_file, &substream)) < 0)
@@ -1802,12 +1802,12 @@ static int snd_pcm_oss_get_formats(struct snd_pcm_oss_file *pcm_oss_file)
                return -ENOMEM;
        _snd_pcm_hw_params_any(params);
        err = snd_pcm_hw_refine(substream, params);
-       format_mask = *hw_param_mask(params, SNDRV_PCM_HW_PARAM_FORMAT); 
+       format_mask = hw_param_mask_c(params, SNDRV_PCM_HW_PARAM_FORMAT);
        kfree(params);
        if (err < 0)
                return err;
        for (fmt = 0; fmt < 32; ++fmt) {
-               if (snd_mask_test(&format_mask, fmt)) {
+               if (snd_mask_test(format_mask, fmt)) {
                        int f = snd_pcm_oss_format_to(fmt);
                        if (f >= 0)
                                formats |= f;

diff --git a/sound/core/oss/pcm_plugin.c b/sound/core/oss/pcm_plugin.c
index 727ac44d39f4a64f7ba203d8dd839caaa66c15ec..cadc937928683cb3abcf7ec8208e8159df31c00f 100644 (file)
--- a/sound/core/oss/pcm_plugin.c
+++ b/sound/core/oss/pcm_plugin.c
@@ -266,7 +266,8 @@ snd_pcm_sframes_t snd_pcm_plug_slave_size(struct snd_pcm_substream *plug, snd_pc
        return frames;
 }
 
-static int snd_pcm_plug_formats(struct snd_mask *mask, snd_pcm_format_t format)
+static int snd_pcm_plug_formats(const struct snd_mask *mask,
+                               snd_pcm_format_t format)
 {
        struct snd_mask formats = *mask;
        u64 linfmts = (SNDRV_PCM_FMTBIT_U8 | SNDRV_PCM_FMTBIT_S8 |
@@ -309,7 +310,7 @@ static snd_pcm_format_t preferred_formats[] = {
 };
 
 snd_pcm_format_t snd_pcm_plug_slave_format(snd_pcm_format_t format,
-                                          struct snd_mask *format_mask)
+                                          const struct snd_mask *format_mask)
 {
        int i;
 

diff --git a/sound/core/oss/pcm_plugin.h b/sound/core/oss/pcm_plugin.h
index a5035c2369a62fccaf55c727b1ef41f70d07f32c..38e2c14cb893ce644343b2b0572e11c32c411d9a 100644 (file)
--- a/sound/core/oss/pcm_plugin.h
+++ b/sound/core/oss/pcm_plugin.h
@@ -126,7 +126,7 @@ int snd_pcm_plug_format_plugins(struct snd_pcm_substream *substream,
                                struct snd_pcm_hw_params *slave_params);
 
 snd_pcm_format_t snd_pcm_plug_slave_format(snd_pcm_format_t format,
-                                          struct snd_mask *format_mask);
+                                          const struct snd_mask *format_mask);
 
 int snd_pcm_plugin_append(struct snd_pcm_plugin *plugin);