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>
---
Changes in v2:
- Added barrier instruction to make the stores available only
after __scm initialization.
- Moved __scm->waitq_comp initialized slight up in program order.
- Added Fixes tag.
drivers/firmware/qcom/qcom_scm.c | 10 +++++-----
1 file changed, 5 insertions(+), 5 deletions(-)
diff --git a/drivers/firmware/qcom/qcom_scm.c b/drivers/firmware/qcom/qcom_scm.c
index e238ebe21099..f014a934a603 100644
--- a/drivers/firmware/qcom/qcom_scm.c
+++ b/drivers/firmware/qcom/qcom_scm.c
@@ -1737,7 +1737,7 @@ static int qcom_scm_qseecom_init(struct qcom_scm *scm)
*/
bool qcom_scm_is_available(void)
{
- return !!__scm;
+ return !!READ_ONCE(__scm);
}
EXPORT_SYMBOL_GPL(qcom_scm_is_available);
@@ -1818,10 +1818,12 @@ 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);
@@ -1853,10 +1855,8 @@ 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) {
--
2.7.4
