[PATCH] PCI/MSI: simplify populate_msi_sysfs()

[PATCH] PCI/MSI: simplify populate_msi_sysfs()

[Jan Beulich]

While originally this was a patch to fix the two memory leaks (which
got preempted by the two commits that went in the day before I wanted
to submit this fix), I think this can (and should) be done more
efficiently:
- swapping the order of the two allocations and storing the
  msi_dev_attr-derived pointer right after allocation, allowing the
  cleanup code to pick things up without extra effort
- using kasprintf() instead of the kmalloc()/sprintf() pair

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/pci/msi.c |   16 ++++++----------
 1 file changed, 6 insertions(+), 10 deletions(-)

--- 3.14-rc4/drivers/pci/msi.c
+++ 3.14-rc4-pci-msi-sysfs-cleanup/drivers/pci/msi.c
@@ -544,22 +544,18 @@ static int populate_msi_sysfs(struct pci
 	if (!msi_attrs)
 		return -ENOMEM;
 	list_for_each_entry(entry, &pdev->msi_list, list) {
-		char *name = kmalloc(20, GFP_KERNEL);
-		if (!name)
-			goto error_attrs;
-
 		msi_dev_attr = kzalloc(sizeof(*msi_dev_attr), GFP_KERNEL);
-		if (!msi_dev_attr) {
-			kfree(name);
+		if (!msi_dev_attr)
 			goto error_attrs;
-		}
+		msi_attrs[count] = &msi_dev_attr->attr;
 
-		sprintf(name, "%d", entry->irq);
 		sysfs_attr_init(&msi_dev_attr->attr);
-		msi_dev_attr->attr.name = name;
+		msi_dev_attr->attr.name = kasprintf(GFP_KERNEL, "%d",
+						    entry->irq);
+		if (!msi_dev_attr->attr.name)
+			goto error_attrs;
 		msi_dev_attr->attr.mode = S_IRUGO;
 		msi_dev_attr->show = msi_mode_show;
-		msi_attrs[count] = &msi_dev_attr->attr;
 		++count;
 	}
 

Re: [PATCH] PCI/MSI: simplify populate_msi_sysfs()

[Greg KH]

On Thu, Feb 27, 2014 at 08:56:35AM +0000, Jan Beulich wrote:
> While originally this was a patch to fix the two memory leaks (which
> got preempted by the two commits that went in the day before I wanted
> to submit this fix), I think this can (and should) be done more
> efficiently:
> - swapping the order of the two allocations and storing the
>   msi_dev_attr-derived pointer right after allocation, allowing the
>   cleanup code to pick things up without extra effort
> - using kasprintf() instead of the kmalloc()/sprintf() pair
> 
> Signed-off-by: Jan Beulich <jbeulich@suse.com>
> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Nice cleanup.

Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Re: [PATCH] PCI/MSI: simplify populate_msi_sysfs()

[Bjorn Helgaas]

On Thu, Feb 27, 2014 at 08:56:35AM +0000, Jan Beulich wrote:
> While originally this was a patch to fix the two memory leaks (which
> got preempted by the two commits that went in the day before I wanted
> to submit this fix), I think this can (and should) be done more
> efficiently:
> - swapping the order of the two allocations and storing the
>   msi_dev_attr-derived pointer right after allocation, allowing the
>   cleanup code to pick things up without extra effort
> - using kasprintf() instead of the kmalloc()/sprintf() pair
> 
> Signed-off-by: Jan Beulich <jbeulich@suse.com>
> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Applied (with Greg's ack) to my pending/msi branch, which will be rebased
and renamed after v3.15-rc1.  Thanks!

> ---
>  drivers/pci/msi.c |   16 ++++++----------
>  1 file changed, 6 insertions(+), 10 deletions(-)
> 
> --- 3.14-rc4/drivers/pci/msi.c
> +++ 3.14-rc4-pci-msi-sysfs-cleanup/drivers/pci/msi.c
> @@ -544,22 +544,18 @@ static int populate_msi_sysfs(struct pci
>  	if (!msi_attrs)
>  		return -ENOMEM;
>  	list_for_each_entry(entry, &pdev->msi_list, list) {
> -		char *name = kmalloc(20, GFP_KERNEL);
> -		if (!name)
> -			goto error_attrs;
> -
>  		msi_dev_attr = kzalloc(sizeof(*msi_dev_attr), GFP_KERNEL);
> -		if (!msi_dev_attr) {
> -			kfree(name);
> +		if (!msi_dev_attr)
>  			goto error_attrs;
> -		}
> +		msi_attrs[count] = &msi_dev_attr->attr;
>  
> -		sprintf(name, "%d", entry->irq);
>  		sysfs_attr_init(&msi_dev_attr->attr);
> -		msi_dev_attr->attr.name = name;
> +		msi_dev_attr->attr.name = kasprintf(GFP_KERNEL, "%d",
> +						    entry->irq);
> +		if (!msi_dev_attr->attr.name)
> +			goto error_attrs;
>  		msi_dev_attr->attr.mode = S_IRUGO;
>  		msi_dev_attr->show = msi_mode_show;
> -		msi_attrs[count] = &msi_dev_attr->attr;
>  		++count;
>  	}
>  
> 
> 
>