[PATCH] Revert "media: iris: reject open() when the session limit is reached"

[Vishnu Reddy]

This reverts commit 397ebadcbc21 ("media: iris: reject open() when the
session limit is reached").

V4L2 does not allow drivers to impose artificial limits on open().
Resource limits must be enforced where the resource is actually
consumed. v4l2-compliance verifies this through testUnlimitedOpens()
and now fails with:

  fail: v4l2-compliance.cpp(773): !ok
        test for unlimited opens: FAIL

Link: https://github.com/gjasny/v4l-utils/blob/master/utils/v4l2-compliance/v4l2-compliance.cpp#L747

The session limit is already enforced at the right place. An instance
that did not fit within max_session_count is not added to
core->instances, and iris_check_session_supported() rejects it with an
error from iris_vb2_queue_setup() and from iris_vb2_start_streaming(),
which is when a firmware session is really needed. Failing open() adds
nothing over that and breaks the compliance requirement.

Fixes: 397ebadcbc21 ("media: iris: reject open() when the session limit is reached")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Vishnu Reddy <busanna.reddy@xxxxxxxxxxxxxxxx>
---
 drivers/media/platform/qcom/iris/iris_vidc.c | 19 ++++++-------------
 1 file changed, 6 insertions(+), 13 deletions(-)

diff --git a/drivers/media/platform/qcom/iris/iris_vidc.c b/drivers/media/platform/qcom/iris/iris_vidc.c
index 05aab6e3005d..a27db6cd969a 100644
--- a/drivers/media/platform/qcom/iris/iris_vidc.c
+++ b/drivers/media/platform/qcom/iris/iris_vidc.c
@@ -56,23 +56,21 @@ void iris_inst_put(struct iris_inst *inst)
 	kref_put(&inst->kref, iris_inst_release);
 }
 
-static int iris_add_session(struct iris_inst *inst)
+static void iris_add_session(struct iris_inst *inst)
 {
 	struct iris_core *core = inst->core;
 	struct iris_inst *iter;
 	u32 count = 0;
 
-	guard(mutex)(&core->lock);
+	mutex_lock(&core->lock);
 
 	list_for_each_entry(iter, &core->instances, list)
 		count++;
 
-	if (count >= core->iris_platform_data->max_session_count)
-		return -EBUSY;
-
-	list_add_tail(&inst->list, &core->instances);
+	if (count < core->iris_platform_data->max_session_count)
+		list_add_tail(&inst->list, &core->instances);
 
-	return 0;
+	mutex_unlock(&core->lock);
 }
 
 static void iris_remove_session(struct iris_inst *inst)
@@ -223,17 +221,12 @@ int iris_open(struct file *filp)
 	if (ret)
 		goto fail_m2m_ctx_release;
 
-	ret = iris_add_session(inst);
-	if (ret)
-		goto fail_inst_deinit;
+	iris_add_session(inst);
 
 	inst->fh.m2m_ctx = inst->m2m_ctx;
 
 	return 0;
 
-fail_inst_deinit:
-	kfree(inst->fmt_src);
-	kfree(inst->fmt_dst);
 fail_m2m_ctx_release:
 	v4l2_m2m_ctx_release(inst->m2m_ctx);
 fail_m2m_release:

---
base-commit: 7649ba73f9e7e1e04d0b46213e39c79ae09dd55c
change-id: 20261031-fix_v4l2_compliance_unlimited_opens-f5b423c1271d

Best regards,
--  
Vishnu Reddy <busanna.reddy@xxxxxxxxxxxxxxxx>