pstream: Pass frame size to keep split memblock parts aligned

`pa_pstream_send_memblock()` would split incoming memblock into parts not
exceeding maximum pool block size.

To make sure split parts of memblock are still frame-aligned add new `align` arg
to `pa_pstream_send_memblock`, find out required alignment from stream sample
format and pass it there. Bump default alignment to 256 which is good up to
32bit 64ch frames.

Part-of: <https://gitlab.freedesktop.org/pulseaudio/pulseaudio/-/merge_requests/780>

5 files changed, 16 insertions, 7 deletions

diff --git a/src/modules/module-tunnel.c b/src/modules/module-tunnel.c
index 61f427bd3..ab094ba4e 100644
--- a/src/modules/module-tunnel.c
+++ b/src/modules/module-tunnel.c
@@ -676,7 +676,7 @@ static int sink_process_msg(pa_msgobject *o, int code, void *data, int64_t offse
              * IO thread context where the rest of the messages are
              * dispatched. Yeah, ugly, but I am a lazy bastard. */
 
-            pa_pstream_send_memblock(u->pstream, u->channel, 0, PA_SEEK_RELATIVE, chunk);
+            pa_pstream_send_memblock(u->pstream, u->channel, 0, PA_SEEK_RELATIVE, chunk, pa_frame_size(&u->sink->sample_spec));
 
             u->receive_counter += chunk->length;
 
diff --git a/src/pulse/stream.c b/src/pulse/stream.c
index 0aa627396..3585b27e8 100644
--- a/src/pulse/stream.c
+++ b/src/pulse/stream.c
@@ -1535,7 +1535,7 @@ int pa_stream_write_ext_free(
         s->write_memblock = NULL;
         s->write_data = NULL;
 
-        pa_pstream_send_memblock(s->context->pstream, s->channel, offset, seek, &chunk);
+        pa_pstream_send_memblock(s->context->pstream, s->channel, offset, seek, &chunk, pa_frame_size(&s->sample_spec));
         pa_memblock_unref(chunk.memblock);
 
     } else {
@@ -1569,7 +1569,7 @@ int pa_stream_write_ext_free(
                 pa_memblock_release(chunk.memblock);
             }
 
-            pa_pstream_send_memblock(s->context->pstream, s->channel, t_offset, t_seek, &chunk);
+            pa_pstream_send_memblock(s->context->pstream, s->channel, t_offset, t_seek, &chunk, pa_frame_size(&s->sample_spec));
 
             t_offset = 0;
             t_seek = PA_SEEK_RELATIVE;
diff --git a/src/pulsecore/protocol-native.c b/src/pulsecore/protocol-native.c
index 672182fbc..1342dee10 100644
--- a/src/pulsecore/protocol-native.c
+++ b/src/pulsecore/protocol-native.c
@@ -1260,7 +1260,7 @@ static void native_connection_send_memblock(pa_native_connection *c) {
             if (schunk.length > r->buffer_attr.fragsize)
                 schunk.length = r->buffer_attr.fragsize;
 
-            pa_pstream_send_memblock(c->pstream, r->index, 0, PA_SEEK_RELATIVE, &schunk);
+            pa_pstream_send_memblock(c->pstream, r->index, 0, PA_SEEK_RELATIVE, &schunk, pa_memblockq_get_base(r->memblockq));
 
             pa_memblockq_drop(r->memblockq, schunk.length);
             pa_memblock_unref(schunk.memblock);
@@ -2535,7 +2535,7 @@ static void setup_srbchannel(pa_native_connection *c, pa_mem_type_t shm_type) {
     mc.memblock = srbt.memblock;
     mc.index = 0;
     mc.length = pa_memblock_get_length(srbt.memblock);
-    pa_pstream_send_memblock(c->pstream, 0, 0, 0, &mc);
+    pa_pstream_send_memblock(c->pstream, 0, 0, 0, &mc, 0);
 
     c->srbpending = srb;
     return;
diff --git a/src/pulsecore/pstream.c b/src/pulsecore/pstream.c
index 7147b776a..ff62f464b 100644
--- a/src/pulsecore/pstream.c
+++ b/src/pulsecore/pstream.c
@@ -82,6 +82,10 @@ typedef uint32_t pa_pstream_descriptor[PA_PSTREAM_DESCRIPTOR_MAX];
  */
 #define FRAME_SIZE_MAX_ALLOW (1024*1024*16)
 
+/* Default memblock alignment used with pa_pstream_send_memblock()
+ */
+#define DEFAULT_PSTREAM_MEMBLOCK_ALIGN (256)
+
 PA_STATIC_FLIST_DECLARE(items, 0, pa_xfree);
 
 struct item_info {
@@ -475,7 +479,7 @@ void pa_pstream_send_packet(pa_pstream*p, pa_packet *packet, pa_cmsg_ancil_data
     p->mainloop->defer_enable(p->defer_event, 1);
 }
 
-void pa_pstream_send_memblock(pa_pstream*p, uint32_t channel, int64_t offset, pa_seek_mode_t seek_mode, const pa_memchunk *chunk) {
+void pa_pstream_send_memblock(pa_pstream*p, uint32_t channel, int64_t offset, pa_seek_mode_t seek_mode, const pa_memchunk *chunk, size_t align) {
     size_t length, idx;
     size_t bsm;
 
@@ -492,6 +496,11 @@ void pa_pstream_send_memblock(pa_pstream*p, uint32_t channel, int64_t offset, pa
 
     bsm = pa_mempool_block_size_max(p->mempool);
 
+    if (align == 0)
+        align = DEFAULT_PSTREAM_MEMBLOCK_ALIGN;
+
+    bsm = (bsm / align) * align;
+
     while (length > 0) {
         struct item_info *i;
         size_t n;
diff --git a/src/pulsecore/pstream.h b/src/pulsecore/pstream.h
index 2bff270ad..88bdca4cc 100644
--- a/src/pulsecore/pstream.h
+++ b/src/pulsecore/pstream.h
@@ -51,7 +51,7 @@ void pa_pstream_unlink(pa_pstream *p);
 int pa_pstream_attach_memfd_shmid(pa_pstream *p, unsigned shm_id, int memfd_fd);
 
 void pa_pstream_send_packet(pa_pstream*p, pa_packet *packet, pa_cmsg_ancil_data *ancil_data);
-void pa_pstream_send_memblock(pa_pstream*p, uint32_t channel, int64_t offset, pa_seek_mode_t seek, const pa_memchunk *chunk);
+void pa_pstream_send_memblock(pa_pstream*p, uint32_t channel, int64_t offset, pa_seek_mode_t seek, const pa_memchunk *chunk, size_t align);
 void pa_pstream_send_release(pa_pstream *p, uint32_t block_id);
 void pa_pstream_send_revoke(pa_pstream *p, uint32_t block_id);