Messages in this thread | | | Date | Tue, 28 Mar 2023 13:34:19 +0300 | Subject | Re: [PATCH] xen/pvcalls: don't call bind_evtchn_to_irqhandler() under lock | From | Oleksandr Tyshchenko <> |
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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);
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