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coresight: cti: Prevent negative values of enable count

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[ Upstream commit 3244fb6dbb ]

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: 835d722ba1 ("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>
This commit is contained in:
James Clark
2023-01-10 11:07:34 +00:00
committed by Greg Kroah-Hartman
parent 065a789b41
commit 14d3414b9d
1 changed files with 9 additions and 2 deletions
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11
drivers/hwtracing/coresight/coresight-cti-core.c
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@@ -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)