On 04/24/2018 05:20 PM, Takashi Iwai wrote:
On Mon, 16 Apr 2018 08:24:51 +0200, Oleksandr Andrushchenko wrote:+static irqreturn_t evtchnl_interrupt_req(int irq, void *dev_id) +{ + struct xen_snd_front_evtchnl *channel = dev_id; + struct xen_snd_front_info *front_info = channel->front_info; + struct xensnd_resp *resp; + RING_IDX i, rp; + unsigned long flags; + + if (unlikely(channel->state != EVTCHNL_STATE_CONNECTED)) + return IRQ_HANDLED; + + spin_lock_irqsave(&front_info->io_lock, flags); + +again: + rp = channel->u.req.ring.sring->rsp_prod; + /* ensure we see queued responses up to rp */ + rmb(); + + for (i = channel->u.req.ring.rsp_cons; i != rp; i++) {I'm not familiar with Xen stuff in general, but through a quick glance, this kind of code worries me a bit. If channel->u.req.ring.rsp_cons has a bogus number, this may lead to a very long loop, no? Better to have a sanity check of the ring buffer size.
In this loop I have: resp = RING_GET_RESPONSE(&channel->u.req.ring, i); and the RING_GET_RESPONSE macro is designed in the way that it wraps around when *i* in the question gets bigger than the ring size: #define RING_GET_REQUEST(_r, _idx) \ (&((_r)->sring->ring[((_idx) & (RING_SIZE(_r) - 1))].req)) So, even if the counter has a bogus number it will not last long
+static irqreturn_t evtchnl_interrupt_evt(int irq, void *dev_id) +{ + struct xen_snd_front_evtchnl *channel = dev_id; + struct xen_snd_front_info *front_info = channel->front_info; + struct xensnd_event_page *page = channel->u.evt.page; + u32 cons, prod; + unsigned long flags; + + if (unlikely(channel->state != EVTCHNL_STATE_CONNECTED)) + return IRQ_HANDLED; + + spin_lock_irqsave(&front_info->io_lock, flags); + + prod = page->in_prod; + /* ensure we see ring contents up to prod */ + virt_rmb(); + if (prod == page->in_cons) + goto out; + + for (cons = page->in_cons; cons != prod; cons++) {Ditto.
Same as above
thanks, Takashi
Thank you, Oleksandr _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxx http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
