Once device_register() failed, we should call put_device() to decrement reference count for cleanup. Or it could cause memory leak.
device_register() includes device_add(). As comment of device_add() says, 'if device_add() succeeds, you should call device_del() when you want to get rid of it. If device_add() has not succeeded, use only put_device() to drop the reference count'.
Found by code review.
Cc: stable@vger.kernel.org Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Ma Ke make24@iscas.ac.cn --- Changes in v4: - deleted the redundant initialization; Changes in v3: - modified the patch as suggestions; Changes in v2: - modified the patch as suggestions. --- arch/arm/common/locomo.c | 13 +++++-------- 1 file changed, 5 insertions(+), 8 deletions(-)
diff --git a/arch/arm/common/locomo.c b/arch/arm/common/locomo.c index cb6ef449b987..45106066a17f 100644 --- a/arch/arm/common/locomo.c +++ b/arch/arm/common/locomo.c @@ -223,10 +223,8 @@ locomo_init_one_child(struct locomo *lchip, struct locomo_dev_info *info) int ret;
dev = kzalloc(sizeof(struct locomo_dev), GFP_KERNEL); - if (!dev) { - ret = -ENOMEM; - goto out; - } + if (!dev) + return -ENOMEM;
/* * If the parent device has a DMA mask associated with it, @@ -254,10 +252,9 @@ locomo_init_one_child(struct locomo *lchip, struct locomo_dev_info *info) NO_IRQ : lchip->irq_base + info->irq[0];
ret = device_register(&dev->dev); - if (ret) { - out: - kfree(dev); - } + if (ret) + put_device(&dev->dev); + return ret; }
On 1/7/25 9:30 PM, Ma Ke wrote:
Once device_register() failed, we should call put_device() to decrement reference count for cleanup. Or it could cause memory leak.
device_register() includes device_add(). As comment of device_add() says, 'if device_add() succeeds, you should call device_del() when you want to get rid of it. If device_add() has not succeeded, use only put_device() to drop the reference count'.
And above device_register() it says:
* NOTE: _Never_ directly free @dev after calling this function, even * if it returned an error! Always use put_device() to give up the * reference initialized in this function instead.
Found by code review.
Cc: stable@vger.kernel.org Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Ma Ke make24@iscas.ac.cn
Looks good to me. Much cleaner result.
Reviewed-by: Alex Elder elder@kernel.org
Changes in v4:
- deleted the redundant initialization;
Changes in v3:
- modified the patch as suggestions;
Changes in v2:
- modified the patch as suggestions.
arch/arm/common/locomo.c | 13 +++++-------- 1 file changed, 5 insertions(+), 8 deletions(-)
diff --git a/arch/arm/common/locomo.c b/arch/arm/common/locomo.c index cb6ef449b987..45106066a17f 100644 --- a/arch/arm/common/locomo.c +++ b/arch/arm/common/locomo.c @@ -223,10 +223,8 @@ locomo_init_one_child(struct locomo *lchip, struct locomo_dev_info *info) int ret; dev = kzalloc(sizeof(struct locomo_dev), GFP_KERNEL);
- if (!dev) {
ret = -ENOMEM;goto out;- }
- if (!dev)
return -ENOMEM;/* * If the parent device has a DMA mask associated with it, @@ -254,10 +252,9 @@ locomo_init_one_child(struct locomo *lchip, struct locomo_dev_info *info) NO_IRQ : lchip->irq_base + info->irq[0]; ret = device_register(&dev->dev);
- if (ret) {
- out:
kfree(dev);- }
- if (ret)
put_device(&dev->dev);- return ret; }
On Wed, Jan 08, 2025 at 11:30:49AM +0800, Ma Ke wrote:
Once device_register() failed, we should call put_device() to decrement reference count for cleanup. Or it could cause memory leak.
device_register() includes device_add(). As comment of device_add() says, 'if device_add() succeeds, you should call device_del() when you want to get rid of it. If device_add() has not succeeded, use only put_device() to drop the reference count'.
I reviewed a previous version of this patch, and commented about the commit message:
The commit message is not quite correct:
"After calling device_register(), the correct way to dispose of the device is to call put_device() as per the device_register() documentation rather than kfree()."
Alex Elder also commented about this. Please fix the commit message. What device_add() doesn't matter, this code isn't calling device_add(), it's calling device_register(), and the comments against device_register() should be appearing in the commit message, not the comments against device_add().
Thanks.
Found by code review.
Cc: stable@vger.kernel.org Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Ma Ke make24@iscas.ac.cn
Changes in v4:
- deleted the redundant initialization;
Changes in v3:
- modified the patch as suggestions;
Changes in v2:
- modified the patch as suggestions.
arch/arm/common/locomo.c | 13 +++++-------- 1 file changed, 5 insertions(+), 8 deletions(-)
diff --git a/arch/arm/common/locomo.c b/arch/arm/common/locomo.c index cb6ef449b987..45106066a17f 100644 --- a/arch/arm/common/locomo.c +++ b/arch/arm/common/locomo.c @@ -223,10 +223,8 @@ locomo_init_one_child(struct locomo *lchip, struct locomo_dev_info *info) int ret; dev = kzalloc(sizeof(struct locomo_dev), GFP_KERNEL);
- if (!dev) {
ret = -ENOMEM;goto out;- }
- if (!dev)
return -ENOMEM;/* * If the parent device has a DMA mask associated with it, @@ -254,10 +252,9 @@ locomo_init_one_child(struct locomo *lchip, struct locomo_dev_info *info) NO_IRQ : lchip->irq_base + info->irq[0]; ret = device_register(&dev->dev);
- if (ret) {
- out:
kfree(dev);- }
- if (ret)
put_device(&dev->dev);- return ret;
} -- 2.25.1
linux-stable-mirror@lists.linaro.org
-
Alex Elder -
Ma Ke -
Russell King (Oracle)