Commit 3244fb6d authored by James Clark's avatar James Clark Committed by Suzuki K Poulose
Browse files

coresight: cti: Prevent negative values of enable count 



Writing 0 to the enable control repeatedly results in a negative value
for enable_req_count. After this, writing 1 to the enable control
appears to not work until the count returns to positive.

Change it so that it's impossible for enable_req_count to be < 0.
Return an error to indicate that the disable request was invalid.

Fixes: 835d722b ("coresight: cti: Initial CoreSight CTI Driver")
Tested-by: default avatarJinlong Mao <quic_jinlmao@quicinc.com>
Signed-off-by: default avatarJames Clark <james.clark@arm.com>
Reviewed-by: default avatarMike Leach <mike.leach@linaro.org>
Signed-off-by: default avatarSuzuki K Poulose <suzuki.poulose@arm.com>
Link: https://lore.kernel.org/r/20230110110736.2709917-2-james.clark@arm.com
parent 589d9282

drivers/hwtracing/coresight/coresight-cti-core.c

+9 −2
Original line number Diff line number Diff line
@@ -151,9 +151,16 @@ static int cti_disable_hw(struct cti_drvdata *drvdata) 
{

	struct cti_config *config = &drvdata->config;

	struct coresight_device *csdev = drvdata->csdev;

	int ret = 0;



	spin_lock(&drvdata->spinlock);



	/* don't allow negative refcounts, return an error */

	if (!atomic_read(&drvdata->config.enable_req_count)) {

		ret = -EINVAL;

		goto cti_not_disabled;

	}



	/* check refcount - disable on 0 */

	if (atomic_dec_return(&drvdata->config.enable_req_count) > 0)

		goto cti_not_disabled;
@@ -171,12 +178,12 @@ static int cti_disable_hw(struct cti_drvdata *drvdata) 
	coresight_disclaim_device_unlocked(csdev);

	CS_LOCK(drvdata->base);

	spin_unlock(&drvdata->spinlock);

	return 0;

	return ret;



	/* not disabled this call */

cti_not_disabled:

	spin_unlock(&drvdata->spinlock);

	return 0;

	return ret;

}



void cti_write_single_reg(struct cti_drvdata *drvdata, int offset, u32 value)