From 1a98502a1bd6b9dd982eb7ceec59ac23d2713d2a Mon Sep 17 00:00:00 2001
From: Richard Fuchs <rfuchs@sipwise.com>
Date: Wed, 19 Mar 2025 12:13:46 -0400
Subject: [PATCH] MT#55283 used aligned memory for bufferpool

Use allocators that return memory blocks aligned to the requested size,
instead of generic malloc. This makes it easier to play tricks with the
memory blocks.

Change-Id: Iad4b1127c76e48c2e9b4ad8489118d4883a24f6a
---
 daemon/helpers.c   |  2 +-
 daemon/main.c      |  4 ++--
 lib/bufferpool.c   | 15 +++++++++++++++
 lib/bufferpool.h   |  3 +++
 t/test-stats.c     |  2 +-
 t/test-transcode.c |  4 ++--
 6 files changed, 24 insertions(+), 6 deletions(-)

diff --git a/daemon/helpers.c b/daemon/helpers.c
index 7e640967a..b77835f53 100644
--- a/daemon/helpers.c
+++ b/daemon/helpers.c
@@ -254,7 +254,7 @@ static void *thread_detach_func(void *d) {
 					dt->priority, strerror(errno));
 	}
 
-	media_bufferpool = bufferpool_new(g_malloc, g_free, 64 * 65536);
+	media_bufferpool = bufferpool_new(bufferpool_aligned_alloc, bufferpool_aligned_free, 64 * 65536);
 #ifdef HAVE_LIBURING
 	if (rtpe_config.common.io_uring)
 		uring_thread_init();
diff --git a/daemon/main.c b/daemon/main.c
index 528055dd5..3cc0ba518 100644
--- a/daemon/main.c
+++ b/daemon/main.c
@@ -1458,7 +1458,7 @@ static void early_init(void) {
 
 #ifdef WITH_TRANSCODING
 static void clib_init(void) {
-	media_bufferpool = bufferpool_new(g_malloc, g_free, 64 * 65536);
+	media_bufferpool = bufferpool_new(bufferpool_aligned_alloc, bufferpool_aligned_free, 64 * 65536);
 #ifdef HAVE_LIBURING
 	if (rtpe_config.common.io_uring)
 		uring_thread_init();
@@ -1506,7 +1506,7 @@ static void kernel_setup(void) {
 	return;
 
 fallback:
-	shm_bufferpool = bufferpool_new(g_malloc, g_free, 4096); // fallback userspace bufferpool
+	shm_bufferpool = bufferpool_new(bufferpool_aligned_alloc, bufferpool_aligned_free, 4096); // fallback userspace bufferpool
 }
 
 
diff --git a/lib/bufferpool.c b/lib/bufferpool.c
index baa8a1076..08e0cfbaa 100644
--- a/lib/bufferpool.c
+++ b/lib/bufferpool.c
@@ -10,6 +10,7 @@ struct bufferpool {
 	void (*dealloc)(void *);
 	void (*dealloc2)(void *, size_t);
 	size_t shard_size;
+	size_t address_mask;
 	mutex_t lock;
 	GQueue empty_shards;
 	GQueue full_shards;
@@ -36,6 +37,8 @@ static struct bufferpool *bufferpool_new_common(void *(*alloc)(size_t), size_t s
 	struct bufferpool *ret = g_new0(__typeof(*ret), 1);
 	ret->alloc = alloc;
 	ret->shard_size = shard_size;
+	ret->address_mask = shard_size - 1;
+	assert((ret->address_mask & shard_size) == 0); // must be a power of two
 	mutex_init(&ret->lock);
 	g_queue_init(&ret->empty_shards);
 	g_queue_init(&ret->full_shards);
@@ -103,6 +106,8 @@ static struct bpool_shard *bufferpool_new_shard(struct bufferpool *bp) {
 	if (!buf)
 		return NULL;
 
+	assert(((size_t) buf & bp->address_mask) == 0);
+
 	struct bpool_shard *ret = g_new0(__typeof(*ret), 1);
 	ret->bp = bp;
 	ret->buf = buf;
@@ -316,3 +321,13 @@ void bufferpool_cleanup(void) {
 	assert(bpool_shards->len == 0);
 	g_ptr_array_free(bpool_shards, true);
 }
+
+void *bufferpool_aligned_alloc(size_t len) {
+	void *m = aligned_alloc(len, len);
+	assert(m != NULL);
+	return m;
+}
+
+void bufferpool_aligned_free(void *p) {
+	free(p);
+}
diff --git a/lib/bufferpool.h b/lib/bufferpool.h
index c28615bf6..aef2e87e4 100644
--- a/lib/bufferpool.h
+++ b/lib/bufferpool.h
@@ -27,6 +27,9 @@ INLINE void *bufferpool_alloc0(struct bufferpool *bp, size_t len) {
 	return ret;
 }
 
+void *bufferpool_aligned_alloc(size_t);
+void bufferpool_aligned_free(void *);
+
 typedef char bp_char;
 G_DEFINE_AUTOPTR_CLEANUP_FUNC(bp_char, bufferpool_unref);
 typedef char bp_void;
diff --git a/t/test-stats.c b/t/test-stats.c
index d739c58d7..f5778369d 100644
--- a/t/test-stats.c
+++ b/t/test-stats.c
@@ -68,7 +68,7 @@ static void __assert_metrics_eq(stats_metric_q *q, const char *b, unsigned int l
 int main(void) {
 	rtpe_common_config_ptr = &rtpe_config.common;
 	bufferpool_init();
-	shm_bufferpool = bufferpool_new(g_malloc, g_free, 4096);
+	shm_bufferpool = bufferpool_new(bufferpool_aligned_alloc, bufferpool_aligned_free, 4096);
 
 	endpoint_parse_any(&rtpe_config.graphite_ep, "1.2.3.4:4567");
 
diff --git a/t/test-transcode.c b/t/test-transcode.c
index aa83ebced..11876828a 100644
--- a/t/test-transcode.c
+++ b/t/test-transcode.c
@@ -418,8 +418,8 @@ static void dtmf(const char *s) {
 int main(void) {
 	rtpe_common_config_ptr = &rtpe_config.common;
 	bufferpool_init();
-	media_bufferpool = bufferpool_new(g_malloc, g_free, 4096);
-	shm_bufferpool = bufferpool_new(g_malloc, g_free, 4096);
+	media_bufferpool = bufferpool_new(bufferpool_aligned_alloc, bufferpool_aligned_free, 4096);
+	shm_bufferpool = bufferpool_new(bufferpool_aligned_alloc, bufferpool_aligned_free, 4096);
 
 	unsigned long random_seed = 0;