Mesa (master): radeon: Add protection against recursive DRM locking.

Alex Deucher agd5f at kemper.freedesktop.org
Wed Aug 12 18:16:29 UTC 2009


Module: Mesa
Branch: master
Commit: 29173d3d5cf02d58e720b5c7fe48a0630c7d5d5f
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=29173d3d5cf02d58e720b5c7fe48a0630c7d5d5f

Author: Pauli Nieminen <suokkos at gmail.com>
Date:   Thu Jul 30 20:17:29 2009 +0300

radeon: Add protection against recursive DRM locking.

Reference counting protects DRM lock call from recursive locking that would
cause hang. Code also adds optional debugging output for recursive call that
is compiled only if NDEBUG is not defined.

This code is not 100% thread safe because mesa doesn't include increment and
test atomic operation. There is built-in gcc functions but they are only
available from gcc 4.2.

---

 .../drivers/dri/radeon/radeon_common_context.c     |    1 +
 .../drivers/dri/radeon/radeon_common_context.h     |    1 +
 src/mesa/drivers/dri/radeon/radeon_lock.c          |   53 +++++++++++++++++++-
 src/mesa/drivers/dri/radeon/radeon_lock.h          |   12 ++++-
 4 files changed, 64 insertions(+), 3 deletions(-)

diff --git a/src/mesa/drivers/dri/radeon/radeon_common_context.c b/src/mesa/drivers/dri/radeon/radeon_common_context.c
index 5e744f9..d68aa2b 100644
--- a/src/mesa/drivers/dri/radeon/radeon_common_context.c
+++ b/src/mesa/drivers/dri/radeon/radeon_common_context.c
@@ -211,6 +211,7 @@ GLboolean radeonInitContext(radeonContextPtr radeon,
 	radeon->dri.screen = sPriv;
 	radeon->dri.hwContext = driContextPriv->hHWContext;
 	radeon->dri.hwLock = &sPriv->pSAREA->lock;
+	radeon->dri.hwLockCount = 0;
 	radeon->dri.fd = sPriv->fd;
 	radeon->dri.drmMinor = sPriv->drm_version.minor;
 
diff --git a/src/mesa/drivers/dri/radeon/radeon_common_context.h b/src/mesa/drivers/dri/radeon/radeon_common_context.h
index d7e94a6..f8e1a25 100644
--- a/src/mesa/drivers/dri/radeon/radeon_common_context.h
+++ b/src/mesa/drivers/dri/radeon/radeon_common_context.h
@@ -365,6 +365,7 @@ struct radeon_dri_mirror {
 
 	drm_context_t hwContext;
 	drm_hw_lock_t *hwLock;
+	int hwLockCount;
 	int fd;
 	int drmMinor;
 };
diff --git a/src/mesa/drivers/dri/radeon/radeon_lock.c b/src/mesa/drivers/dri/radeon/radeon_lock.c
index 2f0ed1c..6294b7e 100644
--- a/src/mesa/drivers/dri/radeon/radeon_lock.c
+++ b/src/mesa/drivers/dri/radeon/radeon_lock.c
@@ -86,8 +86,34 @@ void radeonGetLock(radeonContextPtr rmesa, GLuint flags)
 
 	rmesa->vtbl.get_lock(rmesa);
 }
-
-void radeon_lock_hardware(radeonContextPtr radeon)
+#ifndef NDEBUG
+struct lock_debug {
+	const char* function;
+	const char* file;
+	int line;
+};
+
+static struct lock_debug ldebug = {0};
+#endif
+
+#if 0
+/** TODO: use atomic operations for reference counting **/
+/** gcc 4.2 has builtin functios for this **/
+#define ATOMIC_INC_AND_FETCH(atomic) __sync_add_and_fetch(&atomic, 1)
+#define ATOMIC_DEC_AND_FETCH(atomic) __sync_sub_and_fetch(&atomic, 1)
+#else
+#define ATOMIC_INC_AND_FETCH(atomic) (++atomic)
+#define ATOMIC_DEC_AND_FETCH(atomic) (--atomic)
+#endif
+
+
+void radeon_lock_hardware(radeonContextPtr radeon
+#ifndef NDEBUG
+		,const char* function
+		,const char* file
+		,const int line
+#endif
+		)
 {
 	char ret = 0;
 	struct radeon_framebuffer *rfb = NULL;
@@ -102,16 +128,39 @@ void radeon_lock_hardware(radeonContextPtr radeon)
 	}
 
 	if (!radeon->radeonScreen->driScreen->dri2.enabled) {
+		if (ATOMIC_INC_AND_FETCH(radeon->dri.hwLockCount) > 1)
+		{
+#ifndef NDEBUG
+			if ( RADEON_DEBUG & DEBUG_SANITY )
+				fprintf(stderr, "*** %d times of recursive call to %s ***\n"
+						"Original call was from %s (file: %s line: %d)\n"
+						"Now call is coming from %s (file: %s line: %d)\n"
+						, radeon->dri.hwLockCount, __FUNCTION__
+						, ldebug.function, ldebug.file, ldebug.line
+						, function, file, line
+					   );
+#endif
+			return;
+		}
 		DRM_CAS(radeon->dri.hwLock, radeon->dri.hwContext,
 			 (DRM_LOCK_HELD | radeon->dri.hwContext), ret );
 		if (ret)
 			radeonGetLock(radeon, 0);
+#ifndef NDEBUG
+		ldebug.function = function;
+		ldebug.file = file;
+		ldebug.line = line;
+#endif
 	}
 }
 
 void radeon_unlock_hardware(radeonContextPtr radeon)
 {
 	if (!radeon->radeonScreen->driScreen->dri2.enabled) {
+		if (ATOMIC_DEC_AND_FETCH(radeon->dri.hwLockCount) > 0)
+		{
+			return;
+		}
 		DRM_UNLOCK( radeon->dri.fd,
 			    radeon->dri.hwLock,
 			    radeon->dri.hwContext );
diff --git a/src/mesa/drivers/dri/radeon/radeon_lock.h b/src/mesa/drivers/dri/radeon/radeon_lock.h
index 2817709..da5a5b4 100644
--- a/src/mesa/drivers/dri/radeon/radeon_lock.h
+++ b/src/mesa/drivers/dri/radeon/radeon_lock.h
@@ -48,12 +48,22 @@ WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 
 extern void radeonGetLock(radeonContextPtr rmesa, GLuint flags);
 
-void radeon_lock_hardware(radeonContextPtr rmesa);
+void radeon_lock_hardware(radeonContextPtr rmesa
+#ifndef NDEBUG
+		,const char* function
+		,const char* file
+		,const int line
+#endif
+		);
 void radeon_unlock_hardware(radeonContextPtr rmesa);
 
 /* Lock the hardware and validate our state.
  */
+#ifdef NDEBUG
 #define LOCK_HARDWARE( rmesa )	radeon_lock_hardware(rmesa)
+#else
+#define LOCK_HARDWARE( rmesa )	radeon_lock_hardware(rmesa, __FUNCTION__, __FILE__, __LINE__)
+#endif
 #define UNLOCK_HARDWARE( rmesa )  radeon_unlock_hardware(rmesa)
 
 #endif




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