Re: [PATCH] power: reset: at91-reset: free resources on exit path

On 31.03.2021 11:18, Nicolas Ferre wrote:

On 09/02/2021 at 12:01, Claudiu Beznea wrote:

quoted

Free resources on exit path (failure path of probe and remove).

I'm not sure we can use this driver as a module anyway.

Otherwise, it looks fine, but isn't it possible to use devm_of_iomap(),
even in loop, and avoid having to deal with exit path?

For:
reset->rstc_base = of_iomap(pdev->dev.of_node, 0);

it should work.

For the maps in the loop I have to double check. Basically, the struct
resource object to pass to devm_of_iomap() is needed and for this the
pointer to a struct platform_device object corresponding to the node we
look for in the loop is needed. So, I think this cannot be done this way.

quoted

Reported-by: kernel test robot <redacted>
Reported-by: Dan Carpenter <redacted>
Signed-off-by: Claudiu Beznea <redacted>
---
  drivers/power/reset/at91-reset.c | 25 ++++++++++++++++++++-----
  1 file changed, 20 insertions(+), 5 deletions(-)

diff --git a/drivers/power/reset/at91-reset.c

b/drivers/power/reset/at91-reset.c
index 3ff9d93a5226..2ff7833153b6 100644

--- a/drivers/power/reset/at91-reset.c
+++ b/drivers/power/reset/at91-reset.c

@@ -206,7 +206,8 @@ static int __init at91_reset_probe(struct

platform_device *pdev)
              if (!reset->ramc_base[idx]) {
                  dev_err(&pdev->dev, "Could not map ram controller
address\n");
                  of_node_put(np);
-                return -ENODEV;
+                ret = -ENODEV;
+                goto unmap;
              }
              idx++;
          }

@@ -218,13 +219,15 @@ static int __init at91_reset_probe(struct

platform_device *pdev)
      reset->args = (u32)match->data;
        reset->sclk = devm_clk_get(&pdev->dev, NULL);
-    if (IS_ERR(reset->sclk))
-        return PTR_ERR(reset->sclk);
+    if (IS_ERR(reset->sclk)) {
+        ret = PTR_ERR(reset->sclk);
+        goto unmap;
+    }
        ret = clk_prepare_enable(reset->sclk);
      if (ret) {
          dev_err(&pdev->dev, "Could not enable slow clock\n");
-        return ret;
+        goto unmap;
      }
        platform_set_drvdata(pdev, reset);

@@ -239,21 +242,33 @@ static int __init at91_reset_probe(struct

platform_device *pdev)
      ret = register_restart_handler(&reset->nb);
      if (ret) {
          clk_disable_unprepare(reset->sclk);
-        return ret;
+        goto unmap;
      }
        at91_reset_status(pdev, reset->rstc_base);
        return 0;
+
+unmap:
+    iounmap(reset->rstc_base);
+    for (idx = 0; idx < ARRAY_SIZE(reset->ramc_base); idx++)
+        iounmap(reset->ramc_base[idx]);

But if we keep this loop, I have the feeling that some kind of
"of_node_put()" is needed as well.

No! In the loop:

for_each_matching_node_and_match(np, at91_ramc_of_match, &match) {
	reset->ramc_lpr = (u32)match->data;
	reset->ramc_base[idx] = of_iomap(np, 0);
	if (!reset->ramc_base[idx]) {
		dev_err(&pdev->dev, "Could not map ram controller address\n");
		of_node_put(np);
		ret = -ENODEV;
		goto unmap;
	}
	idx++;
}

the of_node_put() is needed only if the loop is interrupted as the macro:
for_each_matching_node_and_match() is defined as follows:

#define for_each_matching_node_and_match(dn, matches, match) \
	for (dn = of_find_matching_node_and_match(NULL, matches, match); \
	     dn; dn = of_find_matching_node_and_match(dn, matches, match))

and of_find_matching_node_and_match() will return a np with refcount
incremented but at the next loop step the of_find_matching_node_and_match()
will be called with the same np pointer and the np refcount will be
decremented.

struct device_node *of_find_matching_node_and_match(
		struct device_node *from,
		const struct of_device_id *matches,
		const struct of_device_id **match)
{
	// ...
	of_node_put(from);
	// ...
}

quoted

+
+    return ret;
  }
    static int __exit at91_reset_remove(struct platform_device *pdev)
  {
      struct at91_reset *reset = platform_get_drvdata(pdev);
+    int idx;
        unregister_restart_handler(&reset->nb);
      clk_disable_unprepare(reset->sclk);
  +    iounmap(reset->rstc_base);
+    for (idx = 0; idx < ARRAY_SIZE(reset->ramc_base); idx++)
+        iounmap(reset->ramc_base[idx]);

Ditto

quoted

+
      return 0;
  }
 

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel