[PATCH v2 2/2] eal/linux: handle interrupt epoll events

[David Marchand]

Hello Kevin,

On Fri, 6 Feb 2026 at 18:21, Kevin Traynor <ktraynor at redhat.com> wrote:
>
> Add handling for epoll error and disconnect conditions EPOLLERR,
> EPOLLHUP and EPOLLRDHUP.
>
> These events indicate that the interrupt file descriptor is in
> an error state or there has been a hangup.
>
> Only do this for interrupts that are read in eal. Interrupts that
> are read outside eal should deal with different interrupt scenarios
> appropriate to their functionality. e.g. virtio interrupt handling
> has reconnect mechanisms for some cases.
>
> Also, treat no bytes read as an error condition.
>
> Bugzilla ID: 1873
> Fixes: af75078fece3 ("first public release")
> Cc: stable at dpdk.org

Cc: Harman.

>
> Signed-off-by: Kevin Traynor <ktraynor at redhat.com>
> ---
>  lib/eal/linux/eal_interrupts.c | 67 ++++++++++++++++++++++------------
>  1 file changed, 44 insertions(+), 23 deletions(-)
>
> diff --git a/lib/eal/linux/eal_interrupts.c b/lib/eal/linux/eal_interrupts.c
> index 9db978923a..68ca0f929e 100644
> --- a/lib/eal/linux/eal_interrupts.c
> +++ b/lib/eal/linux/eal_interrupts.c
> @@ -887,4 +887,26 @@ rte_intr_disable(const struct rte_intr_handle *intr_handle)
>  }
>
> +static void
> +eal_intr_source_remove_and_free(struct rte_intr_source *src)
> +{
> +       struct rte_intr_callback *cb, *next;
> +
> +       /* Remove the interrupt source */
> +       rte_spinlock_lock(&intr_lock);
> +       TAILQ_REMOVE(&intr_sources, src, next);
> +       rte_spinlock_unlock(&intr_lock);
> +
> +       /* Free callbacks */
> +       for (cb = TAILQ_FIRST(&src->callbacks); cb; cb = next) {
> +               next = TAILQ_NEXT(cb, next);
> +               TAILQ_REMOVE(&src->callbacks, cb, next);
> +               free(cb);
> +       }
> +
> +       /* Free the interrupt source */
> +       rte_intr_instance_free(src->intr_handle);
> +       free(src);
> +}
> +
>  static int
>  eal_intr_process_interrupts(struct epoll_event *events, int nfds)
> @@ -952,4 +974,16 @@ eal_intr_process_interrupts(struct epoll_event *events, int nfds)
>
>                 if (bytes_read > 0) {
> +                       /**
> +                        * Check for epoll error or disconnect events for
> +                        * interrupts that are read directly in eal.
> +                        */
> +                       if (events[n].events & (EPOLLERR | EPOLLHUP | EPOLLRDHUP)) {
> +                               EAL_LOG(INFO, "Disconnect condition on fd %d "

This is an anormal situation, I would make this log level the same as
other logs below.

The fact that the interrupt fd gets into this state should be
something to report and investigate.


> +                                       "(events=0x%x), removing from epoll",
> +                                       events[n].data.fd, events[n].events);
> +                               eal_intr_source_remove_and_free(src);
> +                               return -1;
> +                       }
> +
>                         /**
>                          * read out to clear the ready-to-be-read flag
> @@ -957,5 +991,7 @@ eal_intr_process_interrupts(struct epoll_event *events, int nfds)
>                          */
>                         bytes_read = read(events[n].data.fd, &buf, bytes_read);
> -                       if (bytes_read < 0) {
> +                       if (bytes_read > 0) {
> +                               call = true;
> +                       } else if (bytes_read < 0) {
>                                 if (errno == EINTR || errno == EWOULDBLOCK)
>                                         continue;
> @@ -965,27 +1001,12 @@ eal_intr_process_interrupts(struct epoll_event *events, int nfds)
>                                         events[n].data.fd,
>                                         strerror(errno));
> -                               /*
> -                                * The device is unplugged or buggy, remove
> -                                * it as an interrupt source and return to
> -                                * force the wait list to be rebuilt.
> -                                */
> -                               rte_spinlock_lock(&intr_lock);
> -                               TAILQ_REMOVE(&intr_sources, src, next);
> -                               rte_spinlock_unlock(&intr_lock);
> -
> -                               for (cb = TAILQ_FIRST(&src->callbacks); cb;
> -                                                       cb = next) {
> -                                       next = TAILQ_NEXT(cb, next);
> -                                       TAILQ_REMOVE(&src->callbacks, cb, next);
> -                                       free(cb);
> -                               }
> -                               rte_intr_instance_free(src->intr_handle);
> -                               free(src);
> -                               return -1;
> -                       } else if (bytes_read == 0)
> -                               EAL_LOG(ERR, "Read nothing from file "
> +                       } else { /* bytes == 0 */

"bytes_read == 0", or remove this comment as the code is quite compact
and leaves little space for wondering what this else block is about.


> +                               EAL_LOG(WARNING, "Read nothing from file "

I would keep this log at the same level than the < 0 condition.
It seems the same type of error.

>                                         "descriptor %d", events[n].data.fd);

And avoid splitting the format string.


> -                       else
> -                               call = true;
> +                       }
> +                       if (bytes_read <= 0) {
> +                               eal_intr_source_remove_and_free(src);
> +                               return -1;
> +                       }
>                 }
>
> --
> 2.52.0
>

Except those nits, the fix looks correct.

Acked-by: David Marchand <david.marchand at redhat.com>




-- 
David Marchand