lkml.org 
[lkml]   [2023]   [Jan]   [10]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH v3 1/3] coresight: cti: Prevent negative values of enable count
Date
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>
---
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 d2cf4f4848e1..838872f2484d 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)
--
2.25.1
\
 
 \ /
  Last update: 2023-03-26 23:34    [W:0.057 / U:1.136 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site