[pulseaudio-discuss] [PATCH 11/11] pulsecore: srbchannel: Enable memfd support; pump protocol version

[Ahmed S. Darwish]

Use memfd blocks for the srbchannel if:

  - we have memfd support compiled in, and ..
  - client supports PA protocol version >= 31, and ..
  - client states that it can handle memfd shared memory

Otherwise fall-back to the regular Posix shm_open() techniques.

Signed-off-by: Ahmed S. Darwish <darwish.07 at gmail.com>
---
 PROTOCOL                        | 15 +++++++++++++++
 configure.ac                    |  2 +-
 src/pulse/context.c             |  2 ++
 src/pulsecore/protocol-native.c | 31 ++++++++++++++++++++++++++++---
 4 files changed, 46 insertions(+), 4 deletions(-)

diff --git a/PROTOCOL b/PROTOCOL
index 3c08fea..e7fdda7 100644
--- a/PROTOCOL
+++ b/PROTOCOL
@@ -371,6 +371,21 @@ PA_COMMAND_DISABLE_SRBCHANNEL
 Tells the client to stop listening on the additional SHM ringbuffer channel.
 Acked by client by sending PA_COMMAND_DISABLE_SRBCHANNEL back.
 
+## v31, implemented by >= 7.0
+
+PA_COMMAND_AUTH
+
+New field, from client to server, specifying whether the client supports
+using memfd shared memory.
+
+The server will use memfd communication if:
+
+- the server has memfd code compiled in, and ..
+- client supports protocol version >= 31, and ..
+- the client states that it can handle memfd shared memory
+
+Otherwise, regular posix SHM is used.
+
 #### If you just changed the protocol, read this
 ## module-tunnel depends on the sink/source/sink-input/source-input protocol
 ## internals, so if you changed these, you might have broken module-tunnel.
diff --git a/configure.ac b/configure.ac
index cee1bb4..85807ab 100644
--- a/configure.ac
+++ b/configure.ac
@@ -40,7 +40,7 @@ AC_SUBST(PA_MINOR, pa_minor)
 AC_SUBST(PA_MAJORMINOR, pa_major.pa_minor)
 
 AC_SUBST(PA_API_VERSION, 12)
-AC_SUBST(PA_PROTOCOL_VERSION, 30)
+AC_SUBST(PA_PROTOCOL_VERSION, 31)
 
 # The stable ABI for client applications, for the version info x:y:z
 # always will hold y=z
diff --git a/src/pulse/context.c b/src/pulse/context.c
index ede01fa..f272cd6 100644
--- a/src/pulse/context.c
+++ b/src/pulse/context.c
@@ -591,6 +591,8 @@ static void setup_context(pa_context *c, pa_iochannel *io) {
     pa_tagstruct_putu32(t, PA_PROTOCOL_VERSION | (c->do_shm ? 0x80000000U : 0));
     pa_tagstruct_put_arbitrary(t, cookie, sizeof(cookie));
 
+    pa_tagstruct_put_boolean(t, pa_memfd_is_supported());
+
 #ifdef HAVE_CREDS
 {
     pa_creds ucred;
diff --git a/src/pulsecore/protocol-native.c b/src/pulsecore/protocol-native.c
index 87d3c01..042f1cd 100644
--- a/src/pulsecore/protocol-native.c
+++ b/src/pulsecore/protocol-native.c
@@ -55,6 +55,7 @@
 #include <pulsecore/core-util.h>
 #include <pulsecore/ipacl.h>
 #include <pulsecore/thread-mq.h>
+#include <pulsecore/memfd.h>
 
 #include "protocol-native.h"
 
@@ -172,6 +173,7 @@ struct pa_native_connection {
     bool authorized:1;
     bool is_local:1;
     uint32_t version;
+    pa_mem_type_t shm_type;
     pa_client *client;
     pa_pstream *pstream;
     pa_pdispatch *pdispatch;
@@ -2607,7 +2609,7 @@ static void setup_srbchannel(pa_native_connection *c) {
         return;
     }
 
-    if (!(rw_mempool = pa_mempool_new(PA_MEMORY_SHARED_POSIX, c->protocol->core->shm_size))) {
+    if (!(rw_mempool = pa_mempool_new(c->shm_type, c->protocol->core->shm_size))) {
         pa_log_warn("Disabling srbchannel, reason: Failed to allocate shared "
                     "writable memory pool.");
         return;
@@ -2658,6 +2660,7 @@ static void command_enable_srbchannel(pa_pdispatch *pd, uint32_t command, uint32
 static void command_auth(pa_pdispatch *pd, uint32_t command, uint32_t tag, pa_tagstruct *t, void *userdata) {
     pa_native_connection *c = PA_NATIVE_CONNECTION(userdata);
     const void*cookie;
+    bool memfd_on_remote = false;
     pa_tagstruct *reply;
     bool shm_on_remote = false, do_shm;
 
@@ -2665,8 +2668,7 @@ static void command_auth(pa_pdispatch *pd, uint32_t command, uint32_t tag, pa_ta
     pa_assert(t);
 
     if (pa_tagstruct_getu32(t, &c->version) < 0 ||
-        pa_tagstruct_get_arbitrary(t, &cookie, PA_NATIVE_COOKIE_LENGTH) < 0 ||
-        !pa_tagstruct_eof(t)) {
+        pa_tagstruct_get_arbitrary(t, &cookie, PA_NATIVE_COOKIE_LENGTH) < 0) {
         protocol_error(c);
         return;
     }
@@ -2685,6 +2687,18 @@ static void command_auth(pa_pdispatch *pd, uint32_t command, uint32_t tag, pa_ta
         c->version &= 0x7FFFFFFFU;
     }
 
+    if (c->version < 31) {
+        if (!pa_tagstruct_eof(t)) {
+            protocol_error(c);
+            return;
+        }
+    } else {
+        if (pa_tagstruct_get_boolean(t, &memfd_on_remote) < 0 || !pa_tagstruct_eof(t)) {
+            protocol_error(c);
+            return;
+        }
+    }
+
     pa_log_debug("Protocol version: remote %u, local %u", c->version, PA_PROTOCOL_VERSION);
 
     pa_proplist_setf(c->client->proplist, "native-protocol.version", "%u", c->version);
@@ -2769,6 +2783,17 @@ static void command_auth(pa_pdispatch *pd, uint32_t command, uint32_t tag, pa_ta
     pa_log_debug("Negotiated SHM: %s", pa_yes_no(do_shm));
     pa_pstream_enable_shm(c->pstream, do_shm);
 
+    c->shm_type = PA_MEMORY_UNDEFINED;
+    if (do_shm) {
+        if (c->version >= 31 && memfd_on_remote && pa_memfd_is_supported())
+            c->shm_type = PA_MEMORY_SHARED_MEMFD;
+        else
+            c->shm_type = PA_MEMORY_SHARED_POSIX;
+
+        pa_log_debug("Memfd possible: %s", pa_yes_no(pa_memfd_is_supported()));
+        pa_log_debug("Negotiated SHM type: %s", pa_mem_type_tostr(c->shm_type));
+    }
+
     reply = reply_new(tag);
     pa_tagstruct_putu32(reply, PA_PROTOCOL_VERSION | (do_shm ? 0x80000000 : 0));
 

-- 
Darwish
http://darwish.chasingpointers.com