diff options
author | Gatis Paeglis <gatis.paeglis@qt.io> | 2018-06-04 17:24:53 +0200 |
---|---|---|
committer | Jani Heikkinen <jani.heikkinen@qt.io> | 2018-06-11 12:19:37 +0000 |
commit | 67227aeffdf94be8d177309d27291d5b3247586c (patch) | |
tree | ebed95ed7af297ac60d965aced787651074d0fb8 /src/plugins/platforms/xcb/qxcbbackingstore.cpp | |
parent | 89f9a3db15940ea87d6ad89f93bfa5aa1d7564fb (diff) |
xcb: fix regression with remote X11 clients
There were several issues here:
We were attempting to use MIT-SHM functions over SSH connection,
which is not supported. X server should detect this and return with
an appropriate error message. It does actually return BadAccess for
non-fd code path, but Qt was stubbornly trying to repeat this action
and always falling back to malloc (during window resizing). For fd
code path we were hitting X server bug, which would result in window
freeze [1].
During the initialization we check if xcb_shm_attach_checked() fails,
and disable MIT-SHM if it does. We use this logic to detect if we
are running remotely, as there are no public APIs for it. This way
we can avoid X server bug and avoid needless calling of code path
which will _always_ fail on a remote X11 connection.
[1] https://lists.x.org/archives/xorg-devel/2018-June/057011.html
Task-number: QTBUG-68449
Task-number: QTBUG-68783
Change-Id: I7ab3dcf0f323fd53001b9f7b88c2cb10809af509
Reviewed-by: Gatis Paeglis <gatis.paeglis@qt.io>
Diffstat (limited to 'src/plugins/platforms/xcb/qxcbbackingstore.cpp')
-rw-r--r-- | src/plugins/platforms/xcb/qxcbbackingstore.cpp | 107 |
1 files changed, 62 insertions, 45 deletions
diff --git a/src/plugins/platforms/xcb/qxcbbackingstore.cpp b/src/plugins/platforms/xcb/qxcbbackingstore.cpp index 8cfcc49f9a..b81cb8efa1 100644 --- a/src/plugins/platforms/xcb/qxcbbackingstore.cpp +++ b/src/plugins/platforms/xcb/qxcbbackingstore.cpp @@ -95,6 +95,9 @@ public: void put(xcb_drawable_t dst, const QRegion ®ion, const QPoint &offset); void preparePaint(const QRegion ®ion); + static bool createSystemVShmSegment(QXcbConnection *c, size_t segmentSize = 1, + xcb_shm_segment_info_t *shm_info = nullptr); + private: void createShmSegment(size_t segmentSize); void destroyShmSegment(size_t segmentSize); @@ -325,15 +328,16 @@ void QXcbBackingStoreImage::createShmSegment(size_t segmentSize) #ifdef XCB_USE_SHM_FD if (connection()->hasShmFd()) { if (Q_UNLIKELY(segmentSize > std::numeric_limits<uint32_t>::max())) { - qWarning("QXcbShmImage: xcb_shm_create_segment() can't be called for size %zu, maximum allowed size is %u", - segmentSize, std::numeric_limits<uint32_t>::max()); + qCWarning(lcQpaXcb, "xcb_shm_create_segment() can't be called for size %zu, maximum" + "allowed size is %u", segmentSize, std::numeric_limits<uint32_t>::max()); return; } + const auto seg = xcb_generate_id(xcb_connection()); auto reply = Q_XCB_REPLY(xcb_shm_create_segment, xcb_connection(), seg, segmentSize, false); if (!reply) { - qWarning("QXcbShmImage: xcb_shm_create_segment() failed for size %zu", segmentSize); + qCWarning(lcQpaXcb, "xcb_shm_create_segment() failed for size %zu", segmentSize); return; } @@ -342,13 +346,13 @@ void QXcbBackingStoreImage::createShmSegment(size_t segmentSize) for (int i = 0; i < reply->nfd; i++) close(fds[i]); - qWarning("QXcbShmImage: failed to get file descriptor for shm segment of size %zu", segmentSize); + qCWarning(lcQpaXcb, "failed to get file descriptor for shm segment of size %zu", segmentSize); return; } void *addr = mmap(nullptr, segmentSize, PROT_READ|PROT_WRITE, MAP_SHARED, fds[0], 0); if (addr == MAP_FAILED) { - qWarning("QXcbShmImage: failed to mmap segment from X server (%d: %s) for size %zu", + qCWarning(lcQpaXcb, "failed to mmap segment from X server (%d: %s) for size %zu", errno, strerror(errno), segmentSize); close(fds[0]); xcb_shm_detach(xcb_connection(), seg); @@ -358,47 +362,54 @@ void QXcbBackingStoreImage::createShmSegment(size_t segmentSize) close(fds[0]); m_shm_info.shmseg = seg; m_shm_info.shmaddr = static_cast<quint8 *>(addr); - m_segmentSize = segmentSize; } else #endif { - const int id = shmget(IPC_PRIVATE, segmentSize, IPC_CREAT | 0600); - if (id == -1) { - qWarning("QXcbShmImage: shmget() failed (%d: %s) for size %zu", - errno, strerror(errno), segmentSize); - return; - } - - void *addr = shmat(id, 0, 0); - if (addr == (void *)-1) { - qWarning("QXcbShmImage: shmat() failed (%d: %s) for id %d", - errno, strerror(errno), id); - return; - } - - if (shmctl(id, IPC_RMID, 0) == -1) - qWarning("QXcbBackingStore: Error while marking the shared memory segment to be destroyed"); + if (createSystemVShmSegment(connection(), segmentSize, &m_shm_info)) + m_segmentSize = segmentSize; + } +} - const auto seg = xcb_generate_id(xcb_connection()); - auto cookie = xcb_shm_attach_checked(xcb_connection(), seg, id, false); - auto *error = xcb_request_check(xcb_connection(), cookie); - if (error) { - connection()->printXcbError("QXcbShmImage: xcb_shm_attach() failed with error", error); - free(error); - if (shmdt(addr) == -1) { - qWarning("QXcbShmImage: shmdt() failed (%d: %s) for %p", - errno, strerror(errno), addr); - } - return; - } +bool QXcbBackingStoreImage::createSystemVShmSegment(QXcbConnection *c, size_t segmentSize, + xcb_shm_segment_info_t *shmInfo) +{ + const int id = shmget(IPC_PRIVATE, segmentSize, IPC_CREAT | 0600); + if (id == -1) { + qCWarning(lcQpaXcb, "shmget() failed (%d: %s) for size %zu", errno, strerror(errno), segmentSize); + return false; + } - m_shm_info.shmseg = seg; - m_shm_info.shmid = id; // unused - m_shm_info.shmaddr = static_cast<quint8 *>(addr); + void *addr = shmat(id, 0, 0); + if (addr == (void *)-1) { + qCWarning(lcQpaXcb, "shmat() failed (%d: %s) for id %d", errno, strerror(errno), id); + return false; + } - m_segmentSize = segmentSize; + if (shmctl(id, IPC_RMID, 0) == -1) + qCWarning(lcQpaXcb, "Error while marking the shared memory segment to be destroyed"); + + const auto seg = xcb_generate_id(c->xcb_connection()); + auto cookie = xcb_shm_attach_checked(c->xcb_connection(), seg, id, false); + auto *error = xcb_request_check(c->xcb_connection(), cookie); + if (error) { + c->printXcbError("xcb_shm_attach() failed with error", error); + free(error); + if (shmdt(addr) == -1) + qCWarning(lcQpaXcb, "shmdt() failed (%d: %s) for %p", errno, strerror(errno), addr); + return false; + } else if (!shmInfo) { // this was a test run, free the allocated test segment + xcb_shm_detach(c->xcb_connection(), seg); + auto shmaddr = static_cast<quint8 *>(addr); + if (shmdt(shmaddr) == -1) + qCWarning(lcQpaXcb, "shmdt() failed (%d: %s) for %p", errno, strerror(errno), shmaddr); + } + if (shmInfo) { + shmInfo->shmseg = seg; + shmInfo->shmid = id; // unused + shmInfo->shmaddr = static_cast<quint8 *>(addr); } + return true; } void QXcbBackingStoreImage::destroyShmSegment(size_t segmentSize) @@ -409,21 +420,21 @@ void QXcbBackingStoreImage::destroyShmSegment(size_t segmentSize) auto cookie = xcb_shm_detach_checked(xcb_connection(), m_shm_info.shmseg); xcb_generic_error_t *error = xcb_request_check(xcb_connection(), cookie); if (error) - connection()->printXcbError("QXcbShmImage: xcb_shm_detach() failed with error", error); + connection()->printXcbError("xcb_shm_detach() failed with error", error); m_shm_info.shmseg = 0; #ifdef XCB_USE_SHM_FD if (connection()->hasShmFd()) { if (munmap(m_shm_info.shmaddr, segmentSize) == -1) { - qWarning("QXcbShmImage: munmap() failed (%d: %s) for %p with size %zu", - errno, strerror(errno), m_shm_info.shmaddr, segmentSize); + qCWarning(lcQpaXcb, "munmap() failed (%d: %s) for %p with size %zu", + errno, strerror(errno), m_shm_info.shmaddr, segmentSize); } } else #endif { if (shmdt(m_shm_info.shmaddr) == -1) { - qWarning("QXcbShmImage: shmdt() failed (%d: %s) for %p", - errno, strerror(errno), m_shm_info.shmaddr); + qCWarning(lcQpaXcb, "shmdt() failed (%d: %s) for %p", + errno, strerror(errno), m_shm_info.shmaddr); } m_shm_info.shmid = 0; // unused } @@ -718,6 +729,12 @@ void QXcbBackingStoreImage::preparePaint(const QRegion ®ion) m_pendingFlush |= region; } +bool QXcbBackingStore::createSystemVShmSegment(QXcbConnection *c, size_t segmentSize, void *shmInfo) +{ + auto info = reinterpret_cast<xcb_shm_segment_info_t *>(shmInfo); + return QXcbBackingStoreImage::createSystemVShmSegment(c, segmentSize, info); +} + QXcbBackingStore::QXcbBackingStore(QWindow *window) : QPlatformBackingStore(window) { @@ -757,7 +774,7 @@ void QXcbBackingStore::beginPaint(const QRegion ®ion) void QXcbBackingStore::endPaint() { if (Q_UNLIKELY(m_paintRegions.isEmpty())) { - qWarning("%s: paint regions empty!", Q_FUNC_INFO); + qCWarning(lcQpaXcb, "%s: paint regions empty!", Q_FUNC_INFO); return; } @@ -811,7 +828,7 @@ void QXcbBackingStore::flush(QWindow *window, const QRegion ®ion, const QPoin QXcbWindow *platformWindow = static_cast<QXcbWindow *>(window->handle()); if (!platformWindow) { - qWarning("QXcbBackingStore::flush: QWindow has no platform window (QTBUG-32681)"); + qCWarning(lcQpaXcb, "%s QWindow has no platform window, see QTBUG-32681", Q_FUNC_INFO); return; } |