Commit 1113e52f authored by Michal Wajdeczko's avatar Michal Wajdeczko
Browse files

drm/xe: Fix potential deadlock in __fini_dbm 



If Doorbell Manager is in unclean state during fini phase, for
debug purposes we try to print it's state, but we missed the fact
that we are already holding a lock so the xe_guc_db_mgr_print()
will deadlock since it also attempts to grab the same lock.

Fixes: 587c7334 ("drm/xe: Introduce GuC Doorbells Manager")
Cc: Piotr Piórkowski <piotr.piorkowski@intel.com>
Reviewed-by: default avatarPiotr Piórkowski <piotr.piorkowski@intel.com>
Link: https://lore.kernel.org/r/20240111185603.673-1-michal.wajdeczko@intel.com


Signed-off-by: default avatarMichal Wajdeczko <michal.wajdeczko@intel.com>
parent 33ff1f21

drivers/gpu/drm/xe/xe_guc_db_mgr.c

+16 −11
Original line number Diff line number Diff line
@@ -46,6 +46,8 @@ static struct xe_device *dbm_to_xe(struct xe_guc_db_mgr *dbm) 
#define dbm_assert(_dbm, _cond)		xe_gt_assert(dbm_to_gt(_dbm), _cond)

#define dbm_mutex(_dbm)			(&dbm_to_guc(_dbm)->submission_state.lock)



static void dbm_print_locked(struct xe_guc_db_mgr *dbm, struct drm_printer *p, int indent);



static void __fini_dbm(struct drm_device *drm, void *arg)

{

	struct xe_guc_db_mgr *dbm = arg;
@@ -59,7 +61,7 @@ static void __fini_dbm(struct drm_device *drm, void *arg) 


		xe_gt_err(dbm_to_gt(dbm), "GuC doorbells manager unclean (%u/%u)\n",

			  weight, dbm->count);

		xe_guc_db_mgr_print(dbm, &p, 1);

		dbm_print_locked(dbm, &p, 1);

	}



	bitmap_free(dbm->bitmap);
@@ -219,14 +221,7 @@ void xe_guc_db_mgr_release_range(struct xe_guc_db_mgr *dbm, 
	mutex_unlock(dbm_mutex(dbm));

}



/**

 * xe_guc_db_mgr_print() - Print status of GuC Doorbells Manager.

 * @dbm: the &xe_guc_db_mgr to print

 * @p: the &drm_printer to print to

 * @indent: tab indentation level

 */

void xe_guc_db_mgr_print(struct xe_guc_db_mgr *dbm,

			 struct drm_printer *p, int indent)

static void dbm_print_locked(struct xe_guc_db_mgr *dbm, struct drm_printer *p, int indent)

{

	unsigned int rs, re;

	unsigned int total;
@@ -235,8 +230,6 @@ void xe_guc_db_mgr_print(struct xe_guc_db_mgr *dbm, 
	if (!dbm->bitmap)

		return;



	mutex_lock(dbm_mutex(dbm));



	total = 0;

	for_each_clear_bitrange(rs, re, dbm->bitmap, dbm->count) {

		drm_printf_indent(p, indent, "available range: %u..%u (%u)\n",
@@ -252,7 +245,19 @@ void xe_guc_db_mgr_print(struct xe_guc_db_mgr *dbm, 
		total += re - rs;

	}

	drm_printf_indent(p, indent, "reserved total: %u\n", total);

}



/**

 * xe_guc_db_mgr_print() - Print status of GuC Doorbells Manager.

 * @dbm: the &xe_guc_db_mgr to print

 * @p: the &drm_printer to print to

 * @indent: tab indentation level

 */

void xe_guc_db_mgr_print(struct xe_guc_db_mgr *dbm,

			 struct drm_printer *p, int indent)

{

	mutex_lock(dbm_mutex(dbm));

	dbm_print_locked(dbm, p, indent);

	mutex_unlock(dbm_mutex(dbm));

}