[PATCH] Revert "memory: ti-aemif: don't needlessly iterate over child nodes"

[PATCH] Revert "memory: ti-aemif: don't needlessly iterate over child nodes"

[Bartosz Golaszewski]

From: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>

This reverts commit 23a641d5c2bce4c723fff9118a5d865ee6b9d05a.

The first-level children of the aemif node are not the device nodes (ones
containing the 'compatible' property) but the chip-select nodes which
instead have their own children.

of_platform_populate() will skip such nodes so we must indeed iterate
over the direct children of the aemif node. The problem here is that we
never call of_platform_depopulate() as it takes the root device as
argument. We only have an unpopulated chip-select nodes so we will leak
these devices if any of the calls to of_platform_populate() fails.

I don't have a batter idea right now but my patch was not correct so we
need to revert it. While at it: at least use the scoped variant of the
OF node iterator. Down the line, we should find a better solution to fix
this potential resource leak in error path.

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
---
 drivers/memory/ti-aemif.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/drivers/memory/ti-aemif.c b/drivers/memory/ti-aemif.c
index 3b546eddf5fe9..d54dc3cfff73c 100644
--- a/drivers/memory/ti-aemif.c
+++ b/drivers/memory/ti-aemif.c
@@ -379,9 +379,11 @@ static int aemif_probe(struct platform_device *pdev)
 	 * child will be probed after the AEMIF timing parameters are set.
 	 */
 	if (np) {
-		ret = devm_of_platform_populate(dev);
-		if (ret)
-			return ret;
+		for_each_available_child_of_node_scoped(np, child_np) {
+			ret = of_platform_populate(child_np, NULL, NULL, dev);
+			if (ret < 0)
+				return ret;
+		}
 	}
 
 	return 0;
-- 
2.43.0

Re: [PATCH] Revert "memory: ti-aemif: don't needlessly iterate over child nodes"

[Krzysztof Kozlowski]

On 24/08/2024 10:02, Bartosz Golaszewski wrote:
> From: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
> 
> This reverts commit 23a641d5c2bce4c723fff9118a5d865ee6b9d05a.
> 
> The first-level children of the aemif node are not the device nodes (ones
> containing the 'compatible' property) but the chip-select nodes which
> instead have their own children.
> 
> of_platform_populate() will skip such nodes so we must indeed iterate
> over the direct children of the aemif node. The problem here is that we
> never call of_platform_depopulate() as it takes the root device as
> argument. We only have an unpopulated chip-select nodes so we will leak
> these devices if any of the calls to of_platform_populate() fails.
> 
> I don't have a batter idea right now but my patch was not correct so we
> need to revert it. While at it: at least use the scoped variant of the
> OF node iterator. Down the line, we should find a better solution to fix
> this potential resource leak in error path.
> 
> Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
> ---
>  drivers/memory/ti-aemif.c | 8 +++++---
>  1 file changed, 5 insertions(+), 3 deletions(-)

I'll drop the original commit, because my upstream (arm/soc) might
question this.

Best regards,
Krzysztof

Re: [PATCH] Revert "memory: ti-aemif: don't needlessly iterate over child nodes"

[Krzysztof Kozlowski]

On 25/08/2024 10:15, Krzysztof Kozlowski wrote:
> On 24/08/2024 10:02, Bartosz Golaszewski wrote:
>> From: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
>>
>> This reverts commit 23a641d5c2bce4c723fff9118a5d865ee6b9d05a.
>>
>> The first-level children of the aemif node are not the device nodes (ones
>> containing the 'compatible' property) but the chip-select nodes which
>> instead have their own children.
>>
>> of_platform_populate() will skip such nodes so we must indeed iterate
>> over the direct children of the aemif node. The problem here is that we
>> never call of_platform_depopulate() as it takes the root device as
>> argument. We only have an unpopulated chip-select nodes so we will leak
>> these devices if any of the calls to of_platform_populate() fails.
>>
>> I don't have a batter idea right now but my patch was not correct so we
>> need to revert it. While at it: at least use the scoped variant of the
>> OF node iterator. Down the line, we should find a better solution to fix
>> this potential resource leak in error path.
>>
>> Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
>> ---
>>  drivers/memory/ti-aemif.c | 8 +++++---
>>  1 file changed, 5 insertions(+), 3 deletions(-)
> 
> I'll drop the original commit, because my upstream (arm/soc) might
> question this.
> 

Dropping is non-trivial, so indeed revert.

Best regards,
Krzysztof

Re: [PATCH] Revert "memory: ti-aemif: don't needlessly iterate over child nodes"

[Krzysztof Kozlowski]

On Sat, 24 Aug 2024 10:02:35 +0200, Bartosz Golaszewski wrote:
> This reverts commit 23a641d5c2bce4c723fff9118a5d865ee6b9d05a.
> 
> The first-level children of the aemif node are not the device nodes (ones
> containing the 'compatible' property) but the chip-select nodes which
> instead have their own children.
> 
> of_platform_populate() will skip such nodes so we must indeed iterate
> over the direct children of the aemif node. The problem here is that we
> never call of_platform_depopulate() as it takes the root device as
> argument. We only have an unpopulated chip-select nodes so we will leak
> these devices if any of the calls to of_platform_populate() fails.
> 
> [...]

Applied, thanks!

[1/1] Revert "memory: ti-aemif: don't needlessly iterate over child nodes"
      https://git.kernel.org/krzk/linux-mem-ctrl/c/c7d2f3fbdf59b206414ddc306b0fb74cd174c0ed

Best regards,
-- 
Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>