LinuxLists.cc - [PATCH 1/1 v2] xen: set error code on failures

2016-12-05 08:23:31

Subject: [PATCH 1/1 v2] xen: set error code on failures

Variable rc is reset in the loop, and its value will be non-negative
during the second and after repeat of the loop. If it fails to allocate
memory then, it may return a non-negative integer, which indicates no
error. This patch fixes the bug, assigning "-ENOMEM" to rc when
kzalloc() or alloc_page() returns NULL, and removing the initialization
of rc outside of the loop.

v1 is reviewed by: Juergen Gross <[email protected]>

Signed-off-by: Pan Bian <[email protected]>
---
drivers/xen/gntalloc.c | 9 ++++++---
1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/drivers/xen/gntalloc.c b/drivers/xen/gntalloc.c
index 7a47c4c..1bf55a3 100644
--- a/drivers/xen/gntalloc.c
+++ b/drivers/xen/gntalloc.c
@@ -127,18 +127,21 @@ static int add_grefs(struct ioctl_gntalloc_alloc_gref *op,
struct gntalloc_gref *gref, *next;

readonly = !(op->flags & GNTALLOC_FLAG_WRITABLE);
- rc = -ENOMEM;
for (i = 0; i < op->count; i++) {
gref = kzalloc(sizeof(*gref), GFP_KERNEL);
- if (!gref)
+ if (!gref) {
+ rc = -ENOMEM;
goto undo;
+ }
list_add_tail(&gref->next_gref, &queue_gref);
list_add_tail(&gref->next_file, &queue_file);
gref->users = 1;
gref->file_index = op->index + i * PAGE_SIZE;
gref->page = alloc_page(GFP_KERNEL|__GFP_ZERO);
- if (!gref->page)
+ if (!gref->page) {
+ rc = -ENOMEM;
goto undo;
+ }

/* Grant foreign access to the page. */
rc = gnttab_grant_foreign_access(op->domid,
--
1.9.1

2016-12-05 09:14:12

by Jürgen Groß

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Subject: Re: [PATCH 1/1 v2] xen: set error code on failures

On 05/12/16 09:23, Pan Bian wrote:
> Variable rc is reset in the loop, and its value will be non-negative
> during the second and after repeat of the loop. If it fails to allocate
> memory then, it may return a non-negative integer, which indicates no
> error. This patch fixes the bug, assigning "-ENOMEM" to rc when
> kzalloc() or alloc_page() returns NULL, and removing the initialization
> of rc outside of the loop.
>
> v1 is reviewed by: Juergen Gross <[email protected]>

Not being a real problem in this case I prefer spelling out explicit
"Acked-by:" or "Reviewed-by:" tags myself.

So for this version you can have:

Reviewed-by: Juergen Gross <[email protected]>

Juergen

>
> Signed-off-by: Pan Bian <[email protected]>
> ---
> drivers/xen/gntalloc.c | 9 ++++++---
> 1 file changed, 6 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/xen/gntalloc.c b/drivers/xen/gntalloc.c
> index 7a47c4c..1bf55a3 100644
> --- a/drivers/xen/gntalloc.c
> +++ b/drivers/xen/gntalloc.c
> @@ -127,18 +127,21 @@ static int add_grefs(struct ioctl_gntalloc_alloc_gref *op,
> struct gntalloc_gref *gref, *next;
>
> readonly = !(op->flags & GNTALLOC_FLAG_WRITABLE);
> - rc = -ENOMEM;
> for (i = 0; i < op->count; i++) {
> gref = kzalloc(sizeof(*gref), GFP_KERNEL);
> - if (!gref)
> + if (!gref) {
> + rc = -ENOMEM;
> goto undo;
> + }
> list_add_tail(&gref->next_gref, &queue_gref);
> list_add_tail(&gref->next_file, &queue_file);
> gref->users = 1;
> gref->file_index = op->index + i * PAGE_SIZE;
> gref->page = alloc_page(GFP_KERNEL|__GFP_ZERO);
> - if (!gref->page)
> + if (!gref->page) {
> + rc = -ENOMEM;
> goto undo;
> + }
>
> /* Grant foreign access to the page. */
> rc = gnttab_grant_foreign_access(op->domid,
>

2016-12-08 06:57:47

by Jürgen Groß

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