From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from unimail.uni-dortmund.de (mx1.hrz.uni-dortmund.de [129.217.128.51]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 891C142B72D; Tue, 28 Apr 2026 12:41:20 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=129.217.128.51 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777380089; cv=none; b=Li7ljSp3S7HQjRdcolRJekawwuWe3GN2KVkuWmwSwmO3TVVmtCYL8jcC+mvWqRszeAKfmj3KSDcUPAtO9RZlzO8mOK5t0owQas/6EI6XNSpx5ATExMl9hPSWTuRx04TPY7svo37DpuwqAwehdQGKwvSYeLGIovgvKXGjyN5iTh4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777380089; c=relaxed/simple; bh=9JqgIkM2EaQpzfx516UaEyGa6SvLHt/t3FChNoNlB4M=; h=From:To:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=MkQV+1/KxYj74RT6X5eTRKSTZXJ5cD+N+Er0aw8a9putznWKTCxMzuJIt6dQgfCAEpUCId67YrEw62OKdPl6H1BIJgCBKTLwJlipJD5pPgFJ3Fpa1fnlUdtt5cT7mhg6xf0FqjxzCT1MpYwnUSncYdrMc2roQ3fi9jX02faXJSc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=tu-dortmund.de; spf=pass smtp.mailfrom=tu-dortmund.de; arc=none smtp.client-ip=129.217.128.51 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=tu-dortmund.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=tu-dortmund.de Received: from simon-Latitude-5450.cni.e-technik.tu-dortmund.de ([129.217.186.62]) (authenticated bits=0) by unimail.uni-dortmund.de (8.18.2/8.18.2) with ESMTPSA id 63SCewwk012433 (version=TLSv1.3 cipher=TLS_AES_256_GCM_SHA384 bits=256 verify=NOT); Tue, 28 Apr 2026 14:41:00 +0200 (CEST) From: Simon Schippers To: willemdebruijn.kernel@gmail.com, jasowang@redhat.com, andrew+netdev@lunn.ch, davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, mst@redhat.com, eperezma@redhat.com, leiyang@redhat.com, stephen@networkplumber.org, jon@nutanix.com, tim.gebauer@tu-dortmund.de, simon.schippers@tu-dortmund.de, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, virtualization@lists.linux.dev Subject: [PATCH net-next v9 3/4] ptr_ring: move free-space check into separate helper Date: Tue, 28 Apr 2026 14:38:58 +0200 Message-ID: <20260428123859.19578-4-simon.schippers@tu-dortmund.de> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260428123859.19578-1-simon.schippers@tu-dortmund.de> References: <20260428123859.19578-1-simon.schippers@tu-dortmund.de> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit This patch moves the check for available free space for a new entry into a separate function. As a result, __ptr_ring_produce() remains logically unchanged, while 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_peek() indicates that space is available again. Co-developed-by: Tim Gebauer Signed-off-by: Tim Gebauer Signed-off-by: Simon Schippers --- include/linux/ptr_ring.h | 14 ++++++++++++-- 1 file changed, 12 insertions(+), 2 deletions(-) diff --git a/include/linux/ptr_ring.h b/include/linux/ptr_ring.h index d2c3629bbe45..b51fe4a484be 100644 --- a/include/linux/ptr_ring.h +++ b/include/linux/ptr_ring.h @@ -96,6 +96,14 @@ static inline bool ptr_ring_full_bh(struct ptr_ring *r) return ret; } +static inline int __ptr_ring_produce_peek(struct ptr_ring *r) +{ + if (unlikely(!r->size) || 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 @@ -103,8 +111,10 @@ static inline bool ptr_ring_full_bh(struct ptr_ring *r) */ 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_produce_peek(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. */ -- 2.43.0