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From: Jaroslav Kysela <perex@perex.cz>
To: ALSA development <alsa-devel@alsa-project.org>
Cc: Takashi Iwai <tiwai@suse.de>, Nathan Chancellor <nathan@kernel.org>
Subject: [PATCH] ALSA: control_led - fix the stack usage (control element ops)
Date: Wed, 14 Apr 2021 12:58:58 +0200
Message-ID: <20210414105858.1937710-1-perex@perex.cz> (raw)

It's a bad idea to allocate big structures on the stack.
Mark the variables as static and add a note for the locking.

Fixes: 22d8de62f11b ("ALSA: control - add generic LED trigger module as the new control layer")
Signed-off-by: Jaroslav Kysela <perex@perex.cz>
Cc: Nathan Chancellor <nathan@kernel.org>
Cc: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: Jaroslav Kysela <perex@perex.cz>
---
 sound/core/control_led.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/sound/core/control_led.c b/sound/core/control_led.c
index 93b201063c7d..25f57c14f294 100644
--- a/sound/core/control_led.c
+++ b/sound/core/control_led.c
@@ -94,11 +94,15 @@ static struct snd_ctl_led *snd_ctl_led_get_by_access(unsigned int access)
 	return &snd_ctl_leds[group];
 }
 
+/*
+ * A note for callers:
+ *   The two static variables info and value are protected using snd_ctl_led_mutex.
+ */
 static int snd_ctl_led_get(struct snd_ctl_led_ctl *lctl)
 {
+	static struct snd_ctl_elem_info info;
+	static struct snd_ctl_elem_value value;
 	struct snd_kcontrol *kctl = lctl->kctl;
-	struct snd_ctl_elem_info info;
-	struct snd_ctl_elem_value value;
 	unsigned int i;
 	int result;
 
-- 
2.30.2

             reply index

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-14 10:58 Jaroslav Kysela [this message]
2021-04-14 12:23 ` Takashi Iwai
2021-04-14 13:53   ` Jaroslav Kysela
  -- strict thread matches above, loose matches on Subject: below --
2021-04-14  9:30 Jaroslav Kysela
2021-04-14  9:44 ` Takashi Iwai
2021-04-14 10:09   ` Jaroslav Kysela
2021-04-14 10:52     ` Takashi Iwai
2021-04-14 10:59       ` Jaroslav Kysela

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