From: James Clark james.clark@arm.com
[ Upstream commit 3244fb6dbbf1ffc114cdf382cc167bdd8c18088a ]
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: 835d722ba10a ("coresight: cti: Initial CoreSight CTI Driver") Tested-by: Jinlong Mao quic_jinlmao@quicinc.com Signed-off-by: James Clark james.clark@arm.com Reviewed-by: Mike Leach mike.leach@linaro.org Signed-off-by: Suzuki K Poulose suzuki.poulose@arm.com Link: https://lore.kernel.org/r/20230110110736.2709917-2-james.clark@arm.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/hwtracing/coresight/coresight-cti-core.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-)
diff --git a/drivers/hwtracing/coresight/coresight-cti-core.c b/drivers/hwtracing/coresight/coresight-cti-core.c index d2cf4f4848e1b..838872f2484d3 100644 --- a/drivers/hwtracing/coresight/coresight-cti-core.c +++ b/drivers/hwtracing/coresight/coresight-cti-core.c @@ -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)