tipc_mon_create() is never called in atomic context.
The call chain ending up at tipc_mon_create() is:
[1] tipc_mon_create() <- tipc_enable_bearer() <- tipc_nl_bearer_enable()
tipc_nl_bearer_enable() calls rtnl_lock(), which indicates this function
is not called in atomic context.
Despite never getting called from atomic context,
tipc_mon_create() calls kzalloc() with GFP_ATOMIC,
which does not sleep for allocation.
GFP_ATOMIC is not necessary and can be replaced with GFP_KERNEL,
which can sleep and improve the possibility of successful allocation.
This is found by a static analysis tool named DCNS written by myself.
And I also manually check it.
Signed-off-by: Jia-Ju Bai <[email protected]>
---
v2:
* Modify the description of GFP_ATOMIC in v1.
Thank Eric for good advice.
v3:
* Modify wrong text in description in v2.
Thank Ying for good advice.
---
net/tipc/monitor.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/net/tipc/monitor.c b/net/tipc/monitor.c
index 9e109bb..9714d80 100644
--- a/net/tipc/monitor.c
+++ b/net/tipc/monitor.c
@@ -604,9 +604,9 @@ int tipc_mon_create(struct net *net, int bearer_id)
if (tn->monitors[bearer_id])
return 0;
- mon = kzalloc(sizeof(*mon), GFP_ATOMIC);
- self = kzalloc(sizeof(*self), GFP_ATOMIC);
- dom = kzalloc(sizeof(*dom), GFP_ATOMIC);
+ mon = kzalloc(sizeof(*mon), GFP_KERNEL);
+ self = kzalloc(sizeof(*self), GFP_KERNEL);
+ dom = kzalloc(sizeof(*dom), GFP_KERNEL);
if (!mon || !self || !dom) {
kfree(mon);
kfree(self);
--
1.9.1
On 04/11/2018 06:24 PM, Jia-Ju Bai wrote:
> tipc_mon_create() is never called in atomic context.
>
> The call chain ending up at tipc_mon_create() is:
> [1] tipc_mon_create() <- tipc_enable_bearer() <- tipc_nl_bearer_enable()
> tipc_nl_bearer_enable() calls rtnl_lock(), which indicates this function
> is not called in atomic context.
>
> Despite never getting called from atomic context,
> tipc_mon_create() calls kzalloc() with GFP_ATOMIC,
> which does not sleep for allocation.
> GFP_ATOMIC is not necessary and can be replaced with GFP_KERNEL,
> which can sleep and improve the possibility of successful allocation.
>
> This is found by a static analysis tool named DCNS written by myself.
> And I also manually check it.
>
> Signed-off-by: Jia-Ju Bai <[email protected]>
Acked-by: Ying Xue <[email protected]>
> ---
> v2:
> * Modify the description of GFP_ATOMIC in v1.
> Thank Eric for good advice.
> v3:
> * Modify wrong text in description in v2.
> Thank Ying for good advice.
> ---
> net/tipc/monitor.c | 6 +++---
> 1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/net/tipc/monitor.c b/net/tipc/monitor.c
> index 9e109bb..9714d80 100644
> --- a/net/tipc/monitor.c
> +++ b/net/tipc/monitor.c
> @@ -604,9 +604,9 @@ int tipc_mon_create(struct net *net, int bearer_id)
> if (tn->monitors[bearer_id])
> return 0;
>
> - mon = kzalloc(sizeof(*mon), GFP_ATOMIC);
> - self = kzalloc(sizeof(*self), GFP_ATOMIC);
> - dom = kzalloc(sizeof(*dom), GFP_ATOMIC);
> + mon = kzalloc(sizeof(*mon), GFP_KERNEL);
> + self = kzalloc(sizeof(*self), GFP_KERNEL);
> + dom = kzalloc(sizeof(*dom), GFP_KERNEL);
> if (!mon || !self || !dom) {
> kfree(mon);
> kfree(self);
>
> -----Original Message-----
> From: Ying Xue [mailto:[email protected]]
> Sent: Wednesday, April 11, 2018 06:27
> To: Jia-Ju Bai <[email protected]>; Jon Maloy
> <[email protected]>; [email protected]
> Cc: [email protected]; [email protected]; linux-
> [email protected]
> Subject: Re: [PATCH v3] net: tipc: Replace GFP_ATOMIC with GFP_KERNEL in
> tipc_mon_create
>
> On 04/11/2018 06:24 PM, Jia-Ju Bai wrote:
> > tipc_mon_create() is never called in atomic context.
> >
> > The call chain ending up at tipc_mon_create() is:
> > [1] tipc_mon_create() <- tipc_enable_bearer() <-
> > tipc_nl_bearer_enable()
> > tipc_nl_bearer_enable() calls rtnl_lock(), which indicates this
> > function is not called in atomic context.
> >
> > Despite never getting called from atomic context,
> > tipc_mon_create() calls kzalloc() with GFP_ATOMIC, which does not
> > sleep for allocation.
> > GFP_ATOMIC is not necessary and can be replaced with GFP_KERNEL,
> which
> > can sleep and improve the possibility of successful allocation.
> >
> > This is found by a static analysis tool named DCNS written by myself.
> > And I also manually check it.
> >
> > Signed-off-by: Jia-Ju Bai <[email protected]>
>
> Acked-by: Ying Xue <[email protected]>
Acked-by: Jon Maloy <[email protected]>
>
> > ---
> > v2:
> > * Modify the description of GFP_ATOMIC in v1.
> > Thank Eric for good advice.
> > v3:
> > * Modify wrong text in description in v2.
> > Thank Ying for good advice.
> > ---
> > net/tipc/monitor.c | 6 +++---
> > 1 file changed, 3 insertions(+), 3 deletions(-)
> >
> > diff --git a/net/tipc/monitor.c b/net/tipc/monitor.c index
> > 9e109bb..9714d80 100644
> > --- a/net/tipc/monitor.c
> > +++ b/net/tipc/monitor.c
> > @@ -604,9 +604,9 @@ int tipc_mon_create(struct net *net, int bearer_id)
> > if (tn->monitors[bearer_id])
> > return 0;
> >
> > - mon = kzalloc(sizeof(*mon), GFP_ATOMIC);
> > - self = kzalloc(sizeof(*self), GFP_ATOMIC);
> > - dom = kzalloc(sizeof(*dom), GFP_ATOMIC);
> > + mon = kzalloc(sizeof(*mon), GFP_KERNEL);
> > + self = kzalloc(sizeof(*self), GFP_KERNEL);
> > + dom = kzalloc(sizeof(*dom), GFP_KERNEL);
> > if (!mon || !self || !dom) {
> > kfree(mon);
> > kfree(self);
> >