* [PATCH] xen/pvcalls: don't call bind_evtchn_to_irqhandler() under lock
@ 2023-03-28 9:39 Juergen Gross
2023-03-28 10:34 ` Oleksandr Tyshchenko
0 siblings, 1 reply; 3+ messages in thread
From: Juergen Gross @ 2023-03-28 9:39 UTC (permalink / raw)
To: linux-kernel
Cc: Juergen Gross, Stefano Stabellini, Oleksandr Tyshchenko,
xen-devel, Dan Carpenter
bind_evtchn_to_irqhandler() shouldn't be called under spinlock, as it
can sleep.
This requires to move the calls of create_active() out of the locked
regions. This is no problem, as the worst which could happen would be
a spurious call of the interrupt handler, causing a spurious wake_up().
Reported-by: Dan Carpenter <error27@gmail.com>
Link: https://lore.kernel.org/lkml/Y+JUIl64UDmdkboh@kadam/
Signed-off-by: Juergen Gross <jgross@suse.com>
---
drivers/xen/pvcalls-front.c | 46 ++++++++++++++++++++++---------------
1 file changed, 27 insertions(+), 19 deletions(-)
diff --git a/drivers/xen/pvcalls-front.c b/drivers/xen/pvcalls-front.c
index d5d589bda243..6e5d712e3115 100644
--- a/drivers/xen/pvcalls-front.c
+++ b/drivers/xen/pvcalls-front.c
@@ -227,22 +227,31 @@ static irqreturn_t pvcalls_front_event_handler(int irq, void *dev_id)
static void free_active_ring(struct sock_mapping *map);
-static void pvcalls_front_free_map(struct pvcalls_bedata *bedata,
- struct sock_mapping *map)
+static void pvcalls_front_destroy_active(struct pvcalls_bedata *bedata,
+ struct sock_mapping *map)
{
int i;
unbind_from_irqhandler(map->active.irq, map);
- spin_lock(&bedata->socket_lock);
- if (!list_empty(&map->list))
- list_del_init(&map->list);
- spin_unlock(&bedata->socket_lock);
+ if (bedata) {
+ spin_lock(&bedata->socket_lock);
+ if (!list_empty(&map->list))
+ list_del_init(&map->list);
+ spin_unlock(&bedata->socket_lock);
+ }
for (i = 0; i < (1 << PVCALLS_RING_ORDER); i++)
gnttab_end_foreign_access(map->active.ring->ref[i], NULL);
gnttab_end_foreign_access(map->active.ref, NULL);
+
free_active_ring(map);
+}
+
+static void pvcalls_front_free_map(struct pvcalls_bedata *bedata,
+ struct sock_mapping *map)
+{
+ pvcalls_front_destroy_active(bedata, map);
kfree(map);
}
@@ -433,19 +442,18 @@ int pvcalls_front_connect(struct socket *sock, struct sockaddr *addr,
pvcalls_exit_sock(sock);
return ret;
}
-
- spin_lock(&bedata->socket_lock);
- ret = get_request(bedata, &req_id);
+ ret = create_active(map, &evtchn);
if (ret < 0) {
- spin_unlock(&bedata->socket_lock);
free_active_ring(map);
pvcalls_exit_sock(sock);
return ret;
}
- ret = create_active(map, &evtchn);
+
+ spin_lock(&bedata->socket_lock);
+ ret = get_request(bedata, &req_id);
if (ret < 0) {
spin_unlock(&bedata->socket_lock);
- free_active_ring(map);
+ pvcalls_front_destroy_active(NULL, map);
pvcalls_exit_sock(sock);
return ret;
}
@@ -821,28 +829,28 @@ int pvcalls_front_accept(struct socket *sock, struct socket *newsock, int flags)
pvcalls_exit_sock(sock);
return ret;
}
- spin_lock(&bedata->socket_lock);
- ret = get_request(bedata, &req_id);
+ ret = create_active(map2, &evtchn);
if (ret < 0) {
+ free_active_ring(map2);
+ kfree(map2);
clear_bit(PVCALLS_FLAG_ACCEPT_INFLIGHT,
(void *)&map->passive.flags);
spin_unlock(&bedata->socket_lock);
- free_active_ring(map2);
- kfree(map2);
pvcalls_exit_sock(sock);
return ret;
}
- ret = create_active(map2, &evtchn);
+ spin_lock(&bedata->socket_lock);
+ ret = get_request(bedata, &req_id);
if (ret < 0) {
- free_active_ring(map2);
- kfree(map2);
clear_bit(PVCALLS_FLAG_ACCEPT_INFLIGHT,
(void *)&map->passive.flags);
spin_unlock(&bedata->socket_lock);
+ pvcalls_front_free_map(bedata, map2);
pvcalls_exit_sock(sock);
return ret;
}
+
list_add_tail(&map2->list, &bedata->socket_mappings);
req = RING_GET_REQUEST(&bedata->ring, req_id);
--
2.35.3
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] xen/pvcalls: don't call bind_evtchn_to_irqhandler() under lock
2023-03-28 9:39 [PATCH] xen/pvcalls: don't call bind_evtchn_to_irqhandler() under lock Juergen Gross
@ 2023-03-28 10:34 ` Oleksandr Tyshchenko
2023-03-28 10:58 ` Juergen Gross
0 siblings, 1 reply; 3+ messages in thread
From: Oleksandr Tyshchenko @ 2023-03-28 10:34 UTC (permalink / raw)
To: Juergen Gross
Cc: Stefano Stabellini, Oleksandr Tyshchenko, xen-devel,
Dan Carpenter, linux-kernel
On 28.03.23 12:39, Juergen Gross wrote:
Hello Juergen
> bind_evtchn_to_irqhandler() shouldn't be called under spinlock, as it
> can sleep.
>
> This requires to move the calls of create_active() out of the locked
> regions. This is no problem, as the worst which could happen would be
> a spurious call of the interrupt handler, causing a spurious wake_up().
>
> Reported-by: Dan Carpenter <error27@gmail.com>
> Link: https://lore.kernel.org/lkml/Y+JUIl64UDmdkboh@kadam/
> Signed-off-by: Juergen Gross <jgross@suse.com>
> ---
> drivers/xen/pvcalls-front.c | 46 ++++++++++++++++++++++---------------
> 1 file changed, 27 insertions(+), 19 deletions(-)
>
> diff --git a/drivers/xen/pvcalls-front.c b/drivers/xen/pvcalls-front.c
> index d5d589bda243..6e5d712e3115 100644
> --- a/drivers/xen/pvcalls-front.c
> +++ b/drivers/xen/pvcalls-front.c
> @@ -227,22 +227,31 @@ static irqreturn_t pvcalls_front_event_handler(int irq, void *dev_id)
>
> static void free_active_ring(struct sock_mapping *map);
>
> -static void pvcalls_front_free_map(struct pvcalls_bedata *bedata,
> - struct sock_mapping *map)
> +static void pvcalls_front_destroy_active(struct pvcalls_bedata *bedata,
> + struct sock_mapping *map)
> {
> int i;
>
> unbind_from_irqhandler(map->active.irq, map);
>
> - spin_lock(&bedata->socket_lock);
> - if (!list_empty(&map->list))
> - list_del_init(&map->list);
> - spin_unlock(&bedata->socket_lock);
> + if (bedata) {
> + spin_lock(&bedata->socket_lock);
> + if (!list_empty(&map->list))
> + list_del_init(&map->list);
> + spin_unlock(&bedata->socket_lock);
> + }
>
> for (i = 0; i < (1 << PVCALLS_RING_ORDER); i++)
> gnttab_end_foreign_access(map->active.ring->ref[i], NULL);
> gnttab_end_foreign_access(map->active.ref, NULL);
> +
> free_active_ring(map);
> +}
> +
> +static void pvcalls_front_free_map(struct pvcalls_bedata *bedata,
> + struct sock_mapping *map)
> +{
> + pvcalls_front_destroy_active(bedata, map);
>
> kfree(map);
> }
> @@ -433,19 +442,18 @@ int pvcalls_front_connect(struct socket *sock, struct sockaddr *addr,
> pvcalls_exit_sock(sock);
> return ret;
> }
> -
> - spin_lock(&bedata->socket_lock);
> - ret = get_request(bedata, &req_id);
> + ret = create_active(map, &evtchn);
> if (ret < 0) {
> - spin_unlock(&bedata->socket_lock);
> free_active_ring(map);
> pvcalls_exit_sock(sock);
> return ret;
> }
> - ret = create_active(map, &evtchn);
> +
> + spin_lock(&bedata->socket_lock);
> + ret = get_request(bedata, &req_id);
> if (ret < 0) {
> spin_unlock(&bedata->socket_lock);
> - free_active_ring(map);
> + pvcalls_front_destroy_active(NULL, map);
> pvcalls_exit_sock(sock);
> return ret;
> }
> @@ -821,28 +829,28 @@ int pvcalls_front_accept(struct socket *sock, struct socket *newsock, int flags)
> pvcalls_exit_sock(sock);
> return ret;
> }
> - spin_lock(&bedata->socket_lock);
> - ret = get_request(bedata, &req_id);
> + ret = create_active(map2, &evtchn);
> if (ret < 0) {
> + free_active_ring(map2);
> + kfree(map2);
> clear_bit(PVCALLS_FLAG_ACCEPT_INFLIGHT,
> (void *)&map->passive.flags);
> spin_unlock(&bedata->socket_lock);
Looks like we also need to remove spin_unlock() above, correct?
> - free_active_ring(map2);
> - kfree(map2);
> pvcalls_exit_sock(sock);
> return ret;
> }
>
> - ret = create_active(map2, &evtchn);
> + spin_lock(&bedata->socket_lock);
> + ret = get_request(bedata, &req_id);
> if (ret < 0) {
> - free_active_ring(map2);
> - kfree(map2);
> clear_bit(PVCALLS_FLAG_ACCEPT_INFLIGHT,
> (void *)&map->passive.flags);
> spin_unlock(&bedata->socket_lock);
> + pvcalls_front_free_map(bedata, map2);
> pvcalls_exit_sock(sock);
> return ret;
> }
> +
> list_add_tail(&map2->list, &bedata->socket_mappings);
>
> req = RING_GET_REQUEST(&bedata->ring, req_id);
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] xen/pvcalls: don't call bind_evtchn_to_irqhandler() under lock
2023-03-28 10:34 ` Oleksandr Tyshchenko
@ 2023-03-28 10:58 ` Juergen Gross
0 siblings, 0 replies; 3+ messages in thread
From: Juergen Gross @ 2023-03-28 10:58 UTC (permalink / raw)
To: Oleksandr Tyshchenko
Cc: Stefano Stabellini, Oleksandr Tyshchenko, xen-devel,
Dan Carpenter, linux-kernel
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On 28.03.23 12:34, Oleksandr Tyshchenko wrote:
>
>
> On 28.03.23 12:39, Juergen Gross wrote:
>
> Hello Juergen
>
>
>> bind_evtchn_to_irqhandler() shouldn't be called under spinlock, as it
>> can sleep.
>>
>> This requires to move the calls of create_active() out of the locked
>> regions. This is no problem, as the worst which could happen would be
>> a spurious call of the interrupt handler, causing a spurious wake_up().
>>
>> Reported-by: Dan Carpenter <error27@gmail.com>
>> Link: https://lore.kernel.org/lkml/Y+JUIl64UDmdkboh@kadam/
>> Signed-off-by: Juergen Gross <jgross@suse.com>
>> ---
>> drivers/xen/pvcalls-front.c | 46 ++++++++++++++++++++++---------------
>> 1 file changed, 27 insertions(+), 19 deletions(-)
>>
>> diff --git a/drivers/xen/pvcalls-front.c b/drivers/xen/pvcalls-front.c
>> index d5d589bda243..6e5d712e3115 100644
>> --- a/drivers/xen/pvcalls-front.c
>> +++ b/drivers/xen/pvcalls-front.c
>> @@ -227,22 +227,31 @@ static irqreturn_t pvcalls_front_event_handler(int irq,
>> void *dev_id)
>> static void free_active_ring(struct sock_mapping *map);
>> -static void pvcalls_front_free_map(struct pvcalls_bedata *bedata,
>> - struct sock_mapping *map)
>> +static void pvcalls_front_destroy_active(struct pvcalls_bedata *bedata,
>> + struct sock_mapping *map)
>> {
>> int i;
>> unbind_from_irqhandler(map->active.irq, map);
>> - spin_lock(&bedata->socket_lock);
>> - if (!list_empty(&map->list))
>> - list_del_init(&map->list);
>> - spin_unlock(&bedata->socket_lock);
>> + if (bedata) {
>> + spin_lock(&bedata->socket_lock);
>> + if (!list_empty(&map->list))
>> + list_del_init(&map->list);
>> + spin_unlock(&bedata->socket_lock);
>> + }
>> for (i = 0; i < (1 << PVCALLS_RING_ORDER); i++)
>> gnttab_end_foreign_access(map->active.ring->ref[i], NULL);
>> gnttab_end_foreign_access(map->active.ref, NULL);
>> +
>> free_active_ring(map);
>> +}
>> +
>> +static void pvcalls_front_free_map(struct pvcalls_bedata *bedata,
>> + struct sock_mapping *map)
>> +{
>> + pvcalls_front_destroy_active(bedata, map);
>> kfree(map);
>> }
>> @@ -433,19 +442,18 @@ int pvcalls_front_connect(struct socket *sock, struct
>> sockaddr *addr,
>> pvcalls_exit_sock(sock);
>> return ret;
>> }
>> -
>> - spin_lock(&bedata->socket_lock);
>> - ret = get_request(bedata, &req_id);
>> + ret = create_active(map, &evtchn);
>> if (ret < 0) {
>> - spin_unlock(&bedata->socket_lock);
>> free_active_ring(map);
>> pvcalls_exit_sock(sock);
>> return ret;
>> }
>> - ret = create_active(map, &evtchn);
>> +
>> + spin_lock(&bedata->socket_lock);
>> + ret = get_request(bedata, &req_id);
>> if (ret < 0) {
>> spin_unlock(&bedata->socket_lock);
>> - free_active_ring(map);
>> + pvcalls_front_destroy_active(NULL, map);
>> pvcalls_exit_sock(sock);
>> return ret;
>> }
>> @@ -821,28 +829,28 @@ int pvcalls_front_accept(struct socket *sock, struct
>> socket *newsock, int flags)
>> pvcalls_exit_sock(sock);
>> return ret;
>> }
>> - spin_lock(&bedata->socket_lock);
>> - ret = get_request(bedata, &req_id);
>> + ret = create_active(map2, &evtchn);
>> if (ret < 0) {
>> + free_active_ring(map2);
>> + kfree(map2);
>> clear_bit(PVCALLS_FLAG_ACCEPT_INFLIGHT,
>> (void *)&map->passive.flags);
>> spin_unlock(&bedata->socket_lock);
>
>
> Looks like we also need to remove spin_unlock() above, correct?
Thanks for catching!
Juergen
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2023-03-28 9:39 [PATCH] xen/pvcalls: don't call bind_evtchn_to_irqhandler() under lock Juergen Gross
2023-03-28 10:34 ` Oleksandr Tyshchenko
2023-03-28 10:58 ` Juergen Gross
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