From 6c424e9d4c92087958928492e2b5635d4d5f2b36 Mon Sep 17 00:00:00 2001 From: Olivier Fourdan Date: Mon, 10 Jan 2022 15:10:07 +0100 Subject: [PATCH] shm: Close file descriptors not needed Commit 5a981ee8 implemented a fallback path for platforms which do not support mremap() such as FreeBSD. To do so, the file descriptor for the mmap() is not closed immediately but instead kept as long as the pool exists. That induces more file descriptors kept open for longer, which in turn may cause problems as wl_shm may be using a lot of file descriptors, especially with Xwayland which can create a lot of pixmaps on behalf of its X11 clients. For platforms where mremap() is available, keeping those file descriptors opened is a bit of a waste and may cause exhaustion of file descriptors sooner that before commit 5a981ee8. Only keep the mmap() file descriptor open on platforms which do not implement mremap() and close it immediately as before on others. Signed-off-by: Olivier Fourdan Closes: https://gitlab.freedesktop.org/xorg/xserver/-/issues/1283 --- src/wayland-shm.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/src/wayland-shm.c b/src/wayland-shm.c index 28c550d..c4cd390 100644 --- a/src/wayland-shm.c +++ b/src/wayland-shm.c @@ -65,10 +65,12 @@ struct wl_shm_pool { char *data; ssize_t size; ssize_t new_size; +#ifndef MREMAP_MAYMOVE /* The following three fields are needed for mremap() emulation. */ int mmap_fd; int mmap_flags; int mmap_prot; +#endif bool sigbus_is_impossible; }; @@ -153,7 +155,9 @@ shm_pool_unref(struct wl_shm_pool *pool, bool external) return; munmap(pool->data, pool->size); +#ifndef MREMAP_MAYMOVE close(pool->mmap_fd); +#endif free(pool); } @@ -344,10 +348,14 @@ shm_create_pool(struct wl_client *client, struct wl_resource *resource, strerror(errno)); goto err_free; } +#ifndef MREMAP_MAYMOVE /* We may need to keep the fd, prot and flags to emulate mremap(). */ pool->mmap_fd = fd; pool->mmap_prot = prot; pool->mmap_flags = flags; +#else + close(fd); +#endif pool->resource = wl_resource_create(client, &wl_shm_pool_interface, 1, id); if (!pool->resource) { -- 2.7.4