diff options
author | Nicolás Reynolds <fauno@endefensadelsl.org> | 2014-05-13 04:08:22 +0000 |
---|---|---|
committer | Nicolás Reynolds <fauno@endefensadelsl.org> | 2014-05-13 04:08:22 +0000 |
commit | af87d2873bcaaf5a93ccf25da80aa670f89fbe96 (patch) | |
tree | 42180666994be8f497d5312e8bcc44bd9c690f7e /extra/libxcb | |
parent | 00b75e94fdb3eedea225ff1192972db1a46c09bd (diff) |
Tue May 13 04:03:53 UTC 2014
Diffstat (limited to 'extra/libxcb')
-rw-r--r-- | extra/libxcb/Ensure-xcb-owns-socket-and-no-other-threads-are-writ.patch | 121 | ||||
-rw-r--r-- | extra/libxcb/PKGBUILD | 13 |
2 files changed, 130 insertions, 4 deletions
diff --git a/extra/libxcb/Ensure-xcb-owns-socket-and-no-other-threads-are-writ.patch b/extra/libxcb/Ensure-xcb-owns-socket-and-no-other-threads-are-writ.patch new file mode 100644 index 000000000..90a236816 --- /dev/null +++ b/extra/libxcb/Ensure-xcb-owns-socket-and-no-other-threads-are-writ.patch @@ -0,0 +1,121 @@ +From be0fe56c3bcad5124dcc6c47a2fad01acd16f71a Mon Sep 17 00:00:00 2001 +From: Keith Packard <keithp@keithp.com> +Date: Mon, 23 Dec 2013 21:15:20 -0800 +Subject: [PATCH] Ensure xcb owns socket and no other threads are writing + before send_request + +send_request may only write to out.queue if no other thread is busy +writing to the network (as that thread may be writing from out.queue). + +send_request may only allocate request sequence numbers if XCB owns +the socket. + +Therefore, send_request must make sure that both conditions are true +when it holds iolock, which can only be done by looping until both +conditions are true without having dropped the lock waiting for the +second condition. + +We choose to get the socket back from Xlib first as get_socket_back +has a complicated test and checking for other threads writing is a +simple in-lined check. + +This also changes the sequence number checks (64k requests with no +reply, 4M request wrapping) to ensure that both conditions are true +before queueing the request. + +Signed-off-by: Keith Packard <keithp@keithp.com> +Reviewed-by: Uli Schlachter <psychon@znc.in> +--- + src/xcb_out.c | 57 ++++++++++++++++++++++++++++++++++++++++----------------- + 1 file changed, 40 insertions(+), 17 deletions(-) + +diff --git a/src/xcb_out.c b/src/xcb_out.c +index 18bb5f9..dc42954 100644 +--- a/src/xcb_out.c ++++ b/src/xcb_out.c +@@ -103,6 +103,33 @@ static void get_socket_back(xcb_connection_t *c) + _xcb_in_replies_done(c); + } + ++static void prepare_socket_request(xcb_connection_t *c) ++{ ++ /* We're about to append data to out.queue, so we need to ++ * atomically test for an external socket owner *and* some other ++ * thread currently writing. ++ * ++ * If we have an external socket owner, we have to get the socket back ++ * before we can use it again. ++ * ++ * If some other thread is writing to the socket, we assume it's ++ * writing from out.queue, and so we can't stick data there. ++ * ++ * We satisfy this condition by first calling get_socket_back ++ * (which may drop the lock, but will return when XCB owns the ++ * socket again) and then checking for another writing thread and ++ * escaping the loop if we're ready to go. ++ */ ++ for (;;) { ++ if(c->has_error) ++ return; ++ get_socket_back(c); ++ if (!c->out.writing) ++ break; ++ pthread_cond_wait(&c->out.cond, &c->iolock); ++ } ++} ++ + /* Public interface */ + + void xcb_prefetch_maximum_request_length(xcb_connection_t *c) +@@ -236,24 +263,23 @@ unsigned int xcb_send_request(xcb_connection_t *c, int flags, struct iovec *vect + + /* get a sequence number and arrange for delivery. */ + pthread_mutex_lock(&c->iolock); +- /* wait for other writing threads to get out of my way. */ +- while(c->out.writing) +- pthread_cond_wait(&c->out.cond, &c->iolock); +- get_socket_back(c); ++ ++ prepare_socket_request(c); + + /* send GetInputFocus (sync_req) when 64k-2 requests have been sent without +- * a reply. */ +- if(req->isvoid && c->out.request == c->in.request_expected + (1 << 16) - 2) +- send_sync(c); +- /* Also send sync_req (could use NoOp) at 32-bit wrap to avoid having ++ * a reply. ++ * Also send sync_req (could use NoOp) at 32-bit wrap to avoid having + * applications see sequence 0 as that is used to indicate +- * an error in sending the request */ +- if((unsigned int) (c->out.request + 1) == 0) ++ * an error in sending the request ++ */ ++ ++ while ((req->isvoid && c->out.request == c->in.request_expected + (1 << 16) - 2) || ++ (unsigned int) (c->out.request + 1) == 0) ++ { + send_sync(c); ++ prepare_socket_request(c); ++ } + +- /* The above send_sync calls could drop the I/O lock, but this +- * thread will still exclude any other thread that tries to write, +- * so the sequence number postconditions still hold. */ + send_request(c, req->isvoid, workaround, flags, vector, veclen); + request = c->has_error ? 0 : c->out.request; + pthread_mutex_unlock(&c->iolock); +@@ -373,10 +399,7 @@ int _xcb_out_send(xcb_connection_t *c, struct iovec *vector, int count) + + void _xcb_out_send_sync(xcb_connection_t *c) + { +- /* wait for other writing threads to get out of my way. */ +- while(c->out.writing) +- pthread_cond_wait(&c->out.cond, &c->iolock); +- get_socket_back(c); ++ prepare_socket_request(c); + send_sync(c); + } + +-- +1.9.2 + diff --git a/extra/libxcb/PKGBUILD b/extra/libxcb/PKGBUILD index 523084ba5..a52a31b5c 100644 --- a/extra/libxcb/PKGBUILD +++ b/extra/libxcb/PKGBUILD @@ -1,11 +1,11 @@ -# $Id: PKGBUILD 202710 2013-12-25 21:25:44Z andyrtr $ +# $Id: PKGBUILD 212300 2014-05-12 07:59:16Z lcarlier $ # Maintainer: Andreas Radke <andyrtr@archlinux.org> # Maintainer: Jan de Groot <jgc@archlinux.org> # Contributor: Alexander Baldeck <alexander@archlinux.org> pkgname=libxcb pkgver=1.10 -pkgrel=1 +pkgrel=2 pkgdesc="X11 client-side library" arch=('i686' 'x86_64') url="http://xcb.freedesktop.org/" @@ -13,14 +13,19 @@ depends=('xcb-proto>=1.10' 'libxdmcp' 'libxau') makedepends=('pkgconfig' 'libxslt' 'python') license=('custom') source=($url/dist/$pkgname-$pkgver.tar.bz2 - libxcb-1.1-no-pthread-stubs.patch) + libxcb-1.1-no-pthread-stubs.patch + Ensure-xcb-owns-socket-and-no-other-threads-are-writ.patch) sha256sums=('98d9ab05b636dd088603b64229dd1ab2d2cc02ab807892e107d674f9c3f2d5b5' - '748ed83af60468a0eb6785222e4a5ca589d28f20b9bfc60d5936ec93b8eef356') + '748ed83af60468a0eb6785222e4a5ca589d28f20b9bfc60d5936ec93b8eef356' + '47de1025bb16446b9e69ff7b6b262a0a1af957d350afe897421b9105c89befeb') prepare() { cd "$pkgname-$pkgver" patch -Np1 -i ../libxcb-1.1-no-pthread-stubs.patch autoreconf -vfi + + # fix FS#40289 merged upstream + patch -Np1 -i ../Ensure-xcb-owns-socket-and-no-other-threads-are-writ.patch } build() { |