From: Takashi Iwai <tiwai@suse.de>
Subject: ALSA: pcm: fix hw_rule deps kABI
Patch-mainline: Never, SLE15-SP2 only
References: bsc#1181014

The recent fix for increasing the hw_rule dependencies breaks the kABI.
For keeping the kABI compatibility, revert the change and adds some
hack to allow the fourth element as the extra dependency without a
sentinel.

Signed-off-by: Takashi Iwai <tiwai@suse.de>

---
 include/sound/pcm.h     |    2 +-
 sound/core/pcm_lib.c    |    5 +++--
 sound/core/pcm_native.c |    9 ++++-----
 3 files changed, 8 insertions(+), 8 deletions(-)

--- a/include/sound/pcm.h
+++ b/include/sound/pcm.h
@@ -223,7 +223,7 @@ typedef int (*snd_pcm_hw_rule_func_t)(st
 struct snd_pcm_hw_rule {
 	unsigned int cond;
 	int var;
-	int deps[5];
+	int deps[4];
 
 	snd_pcm_hw_rule_func_t func;
 	void *private;
--- a/sound/core/pcm_lib.c
+++ b/sound/core/pcm_lib.c
@@ -1135,11 +1135,12 @@ int snd_pcm_hw_rule_add(struct snd_pcm_r
 	c->private = private;
 	k = 0;
 	while (1) {
-		if (snd_BUG_ON(k >= ARRAY_SIZE(c->deps))) {
+		if (k < ARRAY_SIZE(c->deps)) {
+			c->deps[k++] = dep;
+		} else if (snd_BUG_ON(dep >= 0)) { /* overflow? */
 			va_end(args);
 			return -EINVAL;
 		}
-		c->deps[k++] = dep;
 		if (dep < 0)
 			break;
 		dep = va_arg(args, int);
--- a/sound/core/pcm_native.c
+++ b/sound/core/pcm_native.c
@@ -382,19 +382,18 @@ retry:
 
 		/*
 		 * The 'deps' array includes maximum four dependencies
-		 * to SNDRV_PCM_HW_PARAM_XXXs for this rule. The fifth
-		 * member of this array is a sentinel and should be
-		 * negative value.
+		 * to SNDRV_PCM_HW_PARAM_XXXs for this rule. It's terminated
+		 * by a sentinel (-1) or fully filled to four items.
 		 *
 		 * This rule should be processed in this time when dependent
 		 * parameters were changed at former applications of the other
 		 * rules.
 		 */
-		for (d = 0; r->deps[d] >= 0; d++) {
+		for (d = 0; d < ARRAY_SIZE(r->deps) && r->deps[d] >= 0; d++) {
 			if (vstamps[r->deps[d]] > rstamps[k])
 				break;
 		}
-		if (r->deps[d] < 0)
+		if (d >= ARRAY_SIZE(r->deps) || r->deps[d] < 0)
 			continue;
 
 		if (trace_hw_mask_param_enabled()) {