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mm/vmpressure.c: fix a signedness bug in vmpressure_register_event()

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The "mode" and "level" variables are enums and in this context GCC will
treat them as unsigned ints so the error handling is never triggered.

I also removed the bogus initializer because it isn't required any more
and it's sort of confusing.

[akpm@linux-foundation.org: reduce implicit and explicit typecasting]
[akpm@linux-foundation.org: fix return value, add comment, per Matthew]
Link: http://lkml.kernel.org/r/20190925110449.GO3264@mwanda
Fixes: 3cadfa2b94 ("mm/vmpressure.c: convert to use match_string() helper")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: David Rientjes <rientjes@google.com>
Reviewed-by: Matthew Wilcox <willy@infradead.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Enrico Weigelt <info@metux.net>
Cc: Kate Stewart <kstewart@linuxfoundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Dan Carpenter 2019-10-06 17:58:28 -07:00 committed by Linus Torvalds
parent 234fdce892
commit 518a867130
1 changed files with 11 additions and 9 deletions
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20
mm/vmpressure.c
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@ -355,6 +355,9 @@ void vmpressure_prio(gfp_t gfp, struct mem_cgroup *memcg, int prio)
* "hierarchy" or "local"). * "hierarchy" or "local").
* *
* To be used as memcg event method. * To be used as memcg event method.
*
* Return: 0 on success, -ENOMEM on memory failure or -EINVAL if @args could
* not be parsed.
*/ */
int vmpressure_register_event(struct mem_cgroup *memcg, int vmpressure_register_event(struct mem_cgroup *memcg,
struct eventfd_ctx *eventfd, const char *args) struct eventfd_ctx *eventfd, const char *args)
@ -362,7 +365,7 @@ int vmpressure_register_event(struct mem_cgroup *memcg,
struct vmpressure *vmpr = memcg_to_vmpressure(memcg); struct vmpressure *vmpr = memcg_to_vmpressure(memcg);
struct vmpressure_event *ev; struct vmpressure_event *ev;
enum vmpressure_modes mode = VMPRESSURE_NO_PASSTHROUGH; enum vmpressure_modes mode = VMPRESSURE_NO_PASSTHROUGH;
enum vmpressure_levels level = -1; enum vmpressure_levels level;
char *spec, *spec_orig; char *spec, *spec_orig;
char *token; char *token;
int ret = 0; int ret = 0;
@ -375,20 +378,18 @@ int vmpressure_register_event(struct mem_cgroup *memcg,
/* Find required level */ /* Find required level */
token = strsep(&spec, ","); token = strsep(&spec, ",");
level = match_string(vmpressure_str_levels, VMPRESSURE_NUM_LEVELS, token); ret = match_string(vmpressure_str_levels, VMPRESSURE_NUM_LEVELS, token);
if (level < 0) { if (ret < 0)
ret = level;
goto out; goto out;
} level = ret;
/* Find optional mode */ /* Find optional mode */
token = strsep(&spec, ","); token = strsep(&spec, ",");
if (token) { if (token) {
mode = match_string(vmpressure_str_modes, VMPRESSURE_NUM_MODES, token); ret = match_string(vmpressure_str_modes, VMPRESSURE_NUM_MODES, token);
if (mode < 0) { if (ret < 0)
ret = mode;
goto out; goto out;
} mode = ret;
} }
ev = kzalloc(sizeof(*ev), GFP_KERNEL); ev = kzalloc(sizeof(*ev), GFP_KERNEL);
@ -404,6 +405,7 @@ int vmpressure_register_event(struct mem_cgroup *memcg,
mutex_lock(&vmpr->events_lock); mutex_lock(&vmpr->events_lock);
list_add(&ev->node, &vmpr->events); list_add(&ev->node, &vmpr->events);
mutex_unlock(&vmpr->events_lock); mutex_unlock(&vmpr->events_lock);
ret = 0;
out: out:
kfree(spec_orig); kfree(spec_orig);
return ret; return ret;