diff options
| author | Simon Schippers <simon.schippers@tu-dortmund.de> | 2026-05-10 17:15:28 +0200 |
|---|---|---|
| committer | Jakub Kicinski <kuba@kernel.org> | 2026-05-13 17:52:55 -0700 |
| commit | fba362c17d9d9211fc51f272156bb84fc23bdf98 (patch) | |
| tree | a7a3c5898149219ff43b29c06f3c2beff28ed2d2 /include | |
| parent | baf808fe4fcd35767ab732b4ab2ea80dabfd97a6 (diff) | |
ptr_ring: move free-space check into separate helper
This patch moves the check for available free space for a new entry into
a separate function. Existing callers that only check for a non-zero
return value are unaffected; __ptr_ring_produce() now returns -EINVAL
for a zero-size ring and -ENOSPC when full, whereas before both cases
returned -ENOSPC. The new helper allows callers to determine in advance
whether subsequent __ptr_ring_produce() calls will succeed. This
information can, for example, be used to temporarily stop producing until
__ptr_ring_check_produce() indicates that space is available again.
Co-developed-by: Tim Gebauer <tim.gebauer@tu-dortmund.de>
Signed-off-by: Tim Gebauer <tim.gebauer@tu-dortmund.de>
Signed-off-by: Simon Schippers <simon.schippers@tu-dortmund.de>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Link: https://patch.msgid.link/20260510151529.43895-4-simon.schippers@tu-dortmund.de
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Diffstat (limited to 'include')
| -rw-r--r-- | include/linux/ptr_ring.h | 20 |
1 files changed, 18 insertions, 2 deletions
diff --git a/include/linux/ptr_ring.h b/include/linux/ptr_ring.h index d2c3629bbe45..c95e891903f0 100644 --- a/include/linux/ptr_ring.h +++ b/include/linux/ptr_ring.h @@ -98,13 +98,29 @@ static inline bool ptr_ring_full_bh(struct ptr_ring *r) /* Note: callers invoking this in a loop must use a compiler barrier, * for example cpu_relax(). Callers must hold producer_lock. + */ +static inline int __ptr_ring_check_produce(struct ptr_ring *r) +{ + if (unlikely(!r->size)) + return -EINVAL; + + if (data_race(r->queue[r->producer])) + return -ENOSPC; + + return 0; +} + +/* Note: callers invoking this in a loop must use a compiler barrier, + * for example cpu_relax(). Callers must hold producer_lock. * Callers are responsible for making sure pointer that is being queued * points to a valid data. */ static inline int __ptr_ring_produce(struct ptr_ring *r, void *ptr) { - if (unlikely(!r->size) || data_race(r->queue[r->producer])) - return -ENOSPC; + int p = __ptr_ring_check_produce(r); + + if (p) + return p; /* Make sure the pointer we are storing points to a valid data. */ /* Pairs with the dependency ordering in __ptr_ring_consume. */ |