diff mbox

iscsi: Fix a sleep-in-atomic bug

Message ID 1496298093.27407.203.camel@haakon3.risingtidesystems.com (mailing list archive)
State Not Applicable, archived
Headers show

Commit Message

Nicholas A. Bellinger June 1, 2017, 6:21 a.m. UTC 
Hi Jia-Ju,

On Wed, 2017-05-31 at 11:26 +0800, Jia-Ju Bai wrote:
> The driver may sleep under a spin lock, and the function call path is:
> iscsit_tpg_enable_portal_group (acquire the lock by spin_lock)
>   iscsi_update_param_value
>     kstrdup(GFP_KERNEL) --> may sleep
> 
> To fix it, the "GFP_KERNEL" is replaced with "GFP_ATOMIC".
> 
> Signed-off-by: Jia-Ju Bai <baijiaju1990@163.com>
> ---
>  drivers/target/iscsi/iscsi_target_parameters.c |    2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)

Btw, the use of tpg->tpg_state_lock in iscsit_tpg_enable_portal_group()
while checking existing state and calling iscsi_update_param_value() is
not necessary, since lio_target_tpg_enable_store() is already holding
iscsit_get_tpg() -> tpg->tpg_access_lock.

How about the following instead to only take tpg->tpg_state_lock when
updating tpg->tpg_state instead..?

Comments

Jia-Ju Bai June 2, 2017, 1:13 a.m. UTC | #1 
On 06/01/2017 02:21 PM, Nicholas A. Bellinger wrote:
> Hi Jia-Ju,
>
> On Wed, 2017-05-31 at 11:26 +0800, Jia-Ju Bai wrote:
>> The driver may sleep under a spin lock, and the function call path is:
>> iscsit_tpg_enable_portal_group (acquire the lock by spin_lock)
>>    iscsi_update_param_value
>>      kstrdup(GFP_KERNEL) -->  may sleep
>>
>> To fix it, the "GFP_KERNEL" is replaced with "GFP_ATOMIC".
>>
>> Signed-off-by: Jia-Ju Bai<baijiaju1990@163.com>
>> ---
>>   drivers/target/iscsi/iscsi_target_parameters.c |    2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
> Btw, the use of tpg->tpg_state_lock in iscsit_tpg_enable_portal_group()
> while checking existing state and calling iscsi_update_param_value() is
> not necessary, since lio_target_tpg_enable_store() is already holding
> iscsit_get_tpg() ->  tpg->tpg_access_lock.
>
> How about the following instead to only take tpg->tpg_state_lock when
> updating tpg->tpg_state instead..?
>
> diff --git a/drivers/target/iscsi/iscsi_target_tpg.c b/drivers/target/iscsi/iscsi_target_tpg.c
> index 2e7e08d..abaabba 100644
> --- a/drivers/target/iscsi/iscsi_target_tpg.c
> +++ b/drivers/target/iscsi/iscsi_target_tpg.c
> @@ -311,11 +311,9 @@ int iscsit_tpg_enable_portal_group(struct iscsi_portal_group *tpg)
>          struct iscsi_tiqn *tiqn = tpg->tpg_tiqn;
>          int ret;
>
> -       spin_lock(&tpg->tpg_state_lock);
>          if (tpg->tpg_state == TPG_STATE_ACTIVE) {
>                  pr_err("iSCSI target portal group: %hu is already"
>                          " active, ignoring request.\n", tpg->tpgt);
> -               spin_unlock(&tpg->tpg_state_lock);
>                  return -EINVAL;
>          }
>          /*
> @@ -324,10 +322,8 @@ int iscsit_tpg_enable_portal_group(struct iscsi_portal_group *tpg)
>           * is enforced (as per default), and remove the NONE option.
>           */
>          param = iscsi_find_param_from_key(AUTHMETHOD, tpg->param_list);
> -       if (!param) {
> -               spin_unlock(&tpg->tpg_state_lock);
> +       if (!param)
>                  return -EINVAL;
> -       }
>
>          if (tpg->tpg_attrib.authentication) {
>                  if (!strcmp(param->value, NONE)) {
> @@ -341,6 +337,7 @@ int iscsit_tpg_enable_portal_group(struct iscsi_portal_group *tpg)
>                          goto err;
>          }
>
> +       spin_lock(&tpg->tpg_state_lock);
>          tpg->tpg_state = TPG_STATE_ACTIVE;
>          spin_unlock(&tpg->tpg_state_lock);
>
> @@ -353,7 +350,6 @@ int iscsit_tpg_enable_portal_group(struct iscsi_portal_group *tpg)
>          return 0;
>
>   err:
> -       spin_unlock(&tpg->tpg_state_lock);
>          return ret;
>   }
>
I think it is fine to me.

Thanks,
Jia-Ju Bai
Nicholas A. Bellinger June 2, 2017, 3:20 a.m. UTC | #2 
On Fri, 2017-06-02 at 09:13 +0800, Jia-Ju Bai wrote:
> On 06/01/2017 02:21 PM, Nicholas A. Bellinger wrote:
> > Hi Jia-Ju,
> >
> > On Wed, 2017-05-31 at 11:26 +0800, Jia-Ju Bai wrote:
> >> The driver may sleep under a spin lock, and the function call path is:
> >> iscsit_tpg_enable_portal_group (acquire the lock by spin_lock)
> >>    iscsi_update_param_value
> >>      kstrdup(GFP_KERNEL) -->  may sleep
> >>
> >> To fix it, the "GFP_KERNEL" is replaced with "GFP_ATOMIC".
> >>
> >> Signed-off-by: Jia-Ju Bai<baijiaju1990@163.com>
> >> ---
> >>   drivers/target/iscsi/iscsi_target_parameters.c |    2 +-
> >>   1 file changed, 1 insertion(+), 1 deletion(-)
> > Btw, the use of tpg->tpg_state_lock in iscsit_tpg_enable_portal_group()
> > while checking existing state and calling iscsi_update_param_value() is
> > not necessary, since lio_target_tpg_enable_store() is already holding
> > iscsit_get_tpg() ->  tpg->tpg_access_lock.
> >
> > How about the following instead to only take tpg->tpg_state_lock when
> > updating tpg->tpg_state instead..?
> >
> > diff --git a/drivers/target/iscsi/iscsi_target_tpg.c b/drivers/target/iscsi/iscsi_target_tpg.c
> > index 2e7e08d..abaabba 100644
> > --- a/drivers/target/iscsi/iscsi_target_tpg.c
> > +++ b/drivers/target/iscsi/iscsi_target_tpg.c
> > @@ -311,11 +311,9 @@ int iscsit_tpg_enable_portal_group(struct iscsi_portal_group *tpg)
> >          struct iscsi_tiqn *tiqn = tpg->tpg_tiqn;
> >          int ret;
> >
> > -       spin_lock(&tpg->tpg_state_lock);
> >          if (tpg->tpg_state == TPG_STATE_ACTIVE) {
> >                  pr_err("iSCSI target portal group: %hu is already"
> >                          " active, ignoring request.\n", tpg->tpgt);
> > -               spin_unlock(&tpg->tpg_state_lock);
> >                  return -EINVAL;
> >          }
> >          /*
> > @@ -324,10 +322,8 @@ int iscsit_tpg_enable_portal_group(struct iscsi_portal_group *tpg)
> >           * is enforced (as per default), and remove the NONE option.
> >           */
> >          param = iscsi_find_param_from_key(AUTHMETHOD, tpg->param_list);
> > -       if (!param) {
> > -               spin_unlock(&tpg->tpg_state_lock);
> > +       if (!param)
> >                  return -EINVAL;
> > -       }
> >
> >          if (tpg->tpg_attrib.authentication) {
> >                  if (!strcmp(param->value, NONE)) {
> > @@ -341,6 +337,7 @@ int iscsit_tpg_enable_portal_group(struct iscsi_portal_group *tpg)
> >                          goto err;
> >          }
> >
> > +       spin_lock(&tpg->tpg_state_lock);
> >          tpg->tpg_state = TPG_STATE_ACTIVE;
> >          spin_unlock(&tpg->tpg_state_lock);
> >
> > @@ -353,7 +350,6 @@ int iscsit_tpg_enable_portal_group(struct iscsi_portal_group *tpg)
> >          return 0;
> >
> >   err:
> > -       spin_unlock(&tpg->tpg_state_lock);
> >          return ret;
> >   }
> >
> I think it is fine to me.
> 
> Thanks,
> Jia-Ju Bai

Applied with your Reported-by and Reviewed-by.

Thanks!
diff mbox

Patch

diff --git a/drivers/target/iscsi/iscsi_target_tpg.c b/drivers/target/iscsi/iscsi_target_tpg.c
index 2e7e08d..abaabba 100644
--- a/drivers/target/iscsi/iscsi_target_tpg.c
+++ b/drivers/target/iscsi/iscsi_target_tpg.c
@@ -311,11 +311,9 @@  int iscsit_tpg_enable_portal_group(struct iscsi_portal_group *tpg)
        struct iscsi_tiqn *tiqn = tpg->tpg_tiqn;
        int ret;
 
-       spin_lock(&tpg->tpg_state_lock);
        if (tpg->tpg_state == TPG_STATE_ACTIVE) {
                pr_err("iSCSI target portal group: %hu is already"
                        " active, ignoring request.\n", tpg->tpgt);
-               spin_unlock(&tpg->tpg_state_lock);
                return -EINVAL;
        }
        /*
@@ -324,10 +322,8 @@  int iscsit_tpg_enable_portal_group(struct iscsi_portal_group *tpg)
         * is enforced (as per default), and remove the NONE option.
         */
        param = iscsi_find_param_from_key(AUTHMETHOD, tpg->param_list);
-       if (!param) {
-               spin_unlock(&tpg->tpg_state_lock);
+       if (!param)
                return -EINVAL;
-       }
 
        if (tpg->tpg_attrib.authentication) {
                if (!strcmp(param->value, NONE)) {
@@ -341,6 +337,7 @@  int iscsit_tpg_enable_portal_group(struct iscsi_portal_group *tpg)
                        goto err;
        }
 
+       spin_lock(&tpg->tpg_state_lock);
        tpg->tpg_state = TPG_STATE_ACTIVE;
        spin_unlock(&tpg->tpg_state_lock);
 
@@ -353,7 +350,6 @@  int iscsit_tpg_enable_portal_group(struct iscsi_portal_group *tpg)
        return 0;
 
 err:
-       spin_unlock(&tpg->tpg_state_lock);
        return ret;
 }