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[1/4] soundwire: intel: fix potential race condition during power down

Message ID 20210727055608.30247-2-yung-chuan.liao@linux.intel.com
State Superseded
Headers show
Series [1/4] soundwire: intel: fix potential race condition during power down | expand

Commit Message

Liao, Bard July 27, 2021, 5:56 a.m. UTC 
From: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>

The power down sequence sets the link_up flag as false outside of the
mutex_lock. This is potentially unsafe.

In additional the flow in that sequence can be improved by first
testing if the link was powered, setting the link_up flag as false and
proceeding with the power down. In case the CPA bits cannot be
cleared, we only flag an error since we cannot deal with interrupts
any longer.

Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Reviewed-by: Ranjani Sridharan <ranjani.sridharan@linux.intel.com>
Signed-off-by: Bard Liao <yung-chuan.liao@linux.intel.com>
---
 drivers/soundwire/intel.c | 23 +++++++++++++----------
 1 file changed, 13 insertions(+), 10 deletions(-)
diff mbox series

Patch

diff --git a/drivers/soundwire/intel.c b/drivers/soundwire/intel.c
index a0178779a5ba..3af922e20e64 100644
--- a/drivers/soundwire/intel.c
+++ b/drivers/soundwire/intel.c
@@ -464,12 +464,14 @@  static int intel_link_power_down(struct sdw_intel *sdw)
 
 	mutex_lock(sdw->link_res->shim_lock);
 
-	intel_shim_master_ip_to_glue(sdw);
-
 	if (!(*shim_mask & BIT(link_id)))
 		dev_err(sdw->cdns.dev,
 			"%s: Unbalanced power-up/down calls\n", __func__);
 
+	sdw->cdns.link_up = false;
+
+	intel_shim_master_ip_to_glue(sdw);
+
 	*shim_mask &= ~BIT(link_id);
 
 	if (!*shim_mask) {
@@ -486,18 +488,19 @@  static int intel_link_power_down(struct sdw_intel *sdw)
 		link_control &=  spa_mask;
 
 		ret = intel_clear_bit(shim, SDW_SHIM_LCTL, link_control, cpa_mask);
+		if (ret < 0) {
+			dev_err(sdw->cdns.dev, "%s: could not power down link\n", __func__);
+
+			/*
+			 * we leave the sdw->cdns.link_up flag as false since we've disabled
+			 * the link at this point and cannot handle interrupts any longer.
+			 */
+		}
 	}
 
 	mutex_unlock(sdw->link_res->shim_lock);
 
-	if (ret < 0) {
-		dev_err(sdw->cdns.dev, "%s: could not power down link\n", __func__);
-
-		return ret;
-	}
-
-	sdw->cdns.link_up = false;
-	return 0;
+	return ret;
 }
 
 static void intel_shim_sync_arm(struct sdw_intel *sdw)