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libdrm: add timeout handling to drmWaitVBlank 

In some cases, vblank interrupts may be disabled or otherwise broken.
The kernel has a 3s timeout builtin to handle these cases, but the X
server's SIGALM for cursor handling may interrupt vblank wait ioctls,
causing libdrm to restart the ioctl, making the kernel's timeout
useless.

This change tracks time across ioctl restarts and returns EBUSY to the
caller if the expected vblank sequence doesn't occur within 1s of the
first call.

Fixes fdo bz #18041, which is caused by a drmWaitVBlank hanging due to
the corresponding pipe getting disabled (thus preventing further events
from coming in).
main
Jesse Barnes 2009-01-07 10:18:08 -08:00
parent a8c548034e
commit f4f76a6894
2 changed files with 20 additions and 1 deletions
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1
libdrm/Makefile.am
View File

@ -23,6 +23,7 @@ SUBDIRS = . intel
libdrm_la_LTLIBRARIES = libdrm.la libdrm_la_LTLIBRARIES = libdrm.la
libdrm_ladir = $(libdir) libdrm_ladir = $(libdir)
libdrm_la_LDFLAGS = -version-number 2:4:0 -no-undefined libdrm_la_LDFLAGS = -version-number 2:4:0 -no-undefined
libdrm_la_LIBADD = -lrt
AM_CFLAGS = -I$(top_srcdir)/shared-core AM_CFLAGS = -I$(top_srcdir)/shared-core
libdrm_la_SOURCES = xf86drm.c xf86drmHash.c xf86drmRandom.c xf86drmSL.c \ libdrm_la_SOURCES = xf86drm.c xf86drmHash.c xf86drmRandom.c xf86drmSL.c \

20
libdrm/xf86drm.c
View File

@ -42,6 +42,7 @@
#include <fcntl.h> #include <fcntl.h>
#include <errno.h> #include <errno.h>
#include <signal.h> #include <signal.h>
#include <time.h>
#include <sys/types.h> #include <sys/types.h>
#include <sys/stat.h> #include <sys/stat.h>
#define stat_t struct stat #define stat_t struct stat
@ -1896,13 +1897,30 @@ int drmScatterGatherFree(int fd, drm_handle_t handle)
*/ */
int drmWaitVBlank(int fd, drmVBlankPtr vbl) int drmWaitVBlank(int fd, drmVBlankPtr vbl)
{ {
struct timespec timeout, cur;
int ret; int ret;
ret = clock_gettime(CLOCK_MONOTONIC, &timeout);
if (ret < 0) {
fprintf(stderr, "clock_gettime failed: %s\n", strerror(ret));
goto out;
}
timeout.tv_sec++;
do { do {
ret = drmIoctl(fd, DRM_IOCTL_WAIT_VBLANK, vbl); ret = ioctl(fd, DRM_IOCTL_WAIT_VBLANK, vbl);
vbl->request.type &= ~DRM_VBLANK_RELATIVE; vbl->request.type &= ~DRM_VBLANK_RELATIVE;
clock_gettime(CLOCK_MONOTONIC, &cur);
/* Timeout after 1s */
if (cur.tv_sec > timeout.tv_sec + 1 ||
cur.tv_sec == timeout.tv_sec && cur.tv_nsec >= timeout.tv_nsec) {
errno = EBUSY;
ret = -1;
break;
}
} while (ret && errno == EINTR); } while (ret && errno == EINTR);
out:
return ret; return ret;
} }