6.6-stable review patch. If anyone has any objections, please let me know.
------------------
From: Mukesh Ojha <quic_mojha@xxxxxxxxxxx>
[ Upstream commit 2e4955167ec5c04534cebea9e8273a907e7a75e1 ]
It is possible qcom_scm_is_available() gives wrong indication that
if __scm is initialized while __scm->dev is not and similar issue
is also possible with __scm->waitq_comp.
Fix this appropriately by the use of release barrier and read barrier
that will make sure if __scm is initialized so, is all of its field
variable.
Fixes: d0f6fa7ba2d6 ("firmware: qcom: scm: Convert SCM to platform driver")
Fixes: 6bf325992236 ("firmware: qcom: scm: Add wait-queue handling logic")
Signed-off-by: Mukesh Ojha <quic_mojha@xxxxxxxxxxx>
Link: https://lore.kernel.org/r/1711034642-22860-4-git-send-email-quic_mojha@xxxxxxxxxxx
Signed-off-by: Bjorn Andersson <andersson@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
drivers/firmware/qcom_scm.c | 10 +++++-----
1 file changed, 5 insertions(+), 5 deletions(-)
diff --git a/drivers/firmware/qcom_scm.c b/drivers/firmware/qcom_scm.c
index 69831f1d91e3f..ff7c155239e31 100644
--- a/drivers/firmware/qcom_scm.c
+++ b/drivers/firmware/qcom_scm.c
@@ -1333,7 +1333,7 @@ static int qcom_scm_find_dload_address(struct device *dev, u64 *addr)
*/
bool qcom_scm_is_available(void)
{
- return !!__scm;
+ return !!READ_ONCE(__scm);
}
EXPORT_SYMBOL_GPL(qcom_scm_is_available);
@@ -1414,10 +1414,12 @@ static int qcom_scm_probe(struct platform_device *pdev)
if (!scm)
return -ENOMEM;
+ scm->dev = &pdev->dev;
ret = qcom_scm_find_dload_address(&pdev->dev, &scm->dload_mode_addr);
if (ret < 0)
return ret;
+ init_completion(&scm->waitq_comp);
mutex_init(&scm->scm_bw_lock);
scm->path = devm_of_icc_get(&pdev->dev, NULL);
@@ -1449,10 +1451,8 @@ static int qcom_scm_probe(struct platform_device *pdev)
if (ret)
return ret;
- __scm = scm;
- __scm->dev = &pdev->dev;
-
- init_completion(&__scm->waitq_comp);
+ /* Let all above stores be available after this */
+ smp_store_release(&__scm, scm);
irq = platform_get_irq_optional(pdev, 0);
if (irq < 0) {
--
2.43.0
