From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-43171.protonmail.ch (mail-43171.protonmail.ch [185.70.43.171]) (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 A36B744DB69; Wed, 27 May 2026 17:41:37 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=185.70.43.171 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779903700; cv=none; b=fJRbTdiVTIWlPto5A0RZj2jlp4mhYAYPtVZqYREfjq2ARK8QBUQrFFd6lz6dm3OMejXZSCjpvs286m4i4M5wO9MMxYdm6vDd3s6Nbl+aPLMIjKse7zCaLCWazlaIyziRdeSPbDlB4dSB/HQd3h2ZVoO7iwfiA7lBzTZmIcfjBtY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779903700; c=relaxed/simple; bh=4jNvNrbzfTwzJjLwSjHboOQERe+1rglIxn+MEh/dkKw=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=BdNUHD32OrDcrZn3h07uWuh7ff05lPUgGdz9ErtdIFZ2UFxYGfraqDOPURygDnKbs90DOrUtR2SgPBPgtyYogp8vGasMkAK5O9lokZlhplDevuBcFMsQJSEoxdpsd9LFUg36Y7QMu5WaREwCAhicBms0giG5VH9HeA7u1wLDwzE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=onurozkan.dev; spf=pass smtp.mailfrom=onurozkan.dev; dkim=pass (2048-bit key) header.d=onurozkan.dev header.i=@onurozkan.dev header.b=n8TN5khM; arc=none smtp.client-ip=185.70.43.171 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=onurozkan.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=onurozkan.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=onurozkan.dev header.i=@onurozkan.dev header.b="n8TN5khM" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=onurozkan.dev; s=protonmail; t=1779903690; x=1780162890; bh=KCC4Lc7DPH4rf7fGK9T09hSlzakl84CnCP2v22rvbnM=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References:From:To: Cc:Date:Subject:Reply-To:Feedback-ID:Message-ID:BIMI-Selector; b=n8TN5khMwMKPivH12GzkakaQHd/6QhxDLUctQWkq+HMjW6dw4GE2Kb1NTaHgKI5rh GKg7i5OQHPshk9jVBuvR+MP2Px2SZ634PiJcfLWzxVPCFL3tgaorYGZLNMnpwyhV7E Cb+eKesAxhXnfWedG1Q40ypIdyBRbUFS9W2Yatio4VBD9yApAuNNYRKxtiiVYXxmzy rFImw0wSOtL5pUwTwADo4uXzUo0DDLHKGpAHx2co3+IKL3rFgFdFRBpta90tqBMuhk kCp3ZALOVJwCT/3zON809bt7Y39gknwi1TcYN08+wcayP/TiCyg/6VAF7u+s9wkuD1 JMZ0OrWnuKLFw== X-Pm-Submission-Id: 4gQcP41xnxz1DDs2 From: =?UTF-8?q?Onur=20=C3=96zkan?= To: rcu@vger.kernel.org, rust-for-linux@vger.kernel.org, linux-kernel@vger.kernel.org Cc: ojeda@kernel.org, boqun@kernel.org, gary@garyguo.net, bjorn3_gh@protonmail.com, lossin@kernel.org, a.hindborg@kernel.org, aliceryhl@google.com, tmgross@umich.edu, dakr@kernel.org, peterz@infradead.org, fujita.tomonori@gmail.com, tamird@kernel.org, jiangshanlai@gmail.com, paulmck@kernel.org, josh@joshtriplett.org, rostedt@goodmis.org, mathieu.desnoyers@efficios.com, =?UTF-8?q?Onur=20=C3=96zkan?= Subject: [PATCH v5 2/4] srcu: expose srcu_readers_active() Date: Wed, 27 May 2026 20:40:43 +0300 Message-ID: <20260527174120.510447-3-work@onurozkan.dev> X-Mailer: git-send-email 2.51.2 In-Reply-To: <20260527174120.510447-1-work@onurozkan.dev> References: <20260527174120.510447-1-work@onurozkan.dev> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Move srcu_readers_active() from kernel/rcu/srcutree.c into include/linux/srcu.h so it can be reused by Rust SRCU helpers. Provide a CONFIG_TINY_SRCU implementation in the header as well so the helper is available regardless of the selected SRCU backend. This is needed by rust/helpers/srcu.c which now adds rust_helper_srcu_readers_active() as a wrapper around the SRCU helper for Rust callers. Signed-off-by: Onur Özkan --- include/linux/srcu.h | 29 +++++++++++++++++++++++++++++ kernel/rcu/srcutiny.c | 2 +- kernel/rcu/srcutree.c | 25 ------------------------- rust/helpers/srcu.c | 5 +++++ 4 files changed, 35 insertions(+), 26 deletions(-) diff --git a/include/linux/srcu.h b/include/linux/srcu.h index 81b1938512d5..5ca35efb4536 100644 --- a/include/linux/srcu.h +++ b/include/linux/srcu.h @@ -92,6 +92,35 @@ void call_srcu(struct srcu_struct *ssp, struct rcu_head *head, void cleanup_srcu_struct(struct srcu_struct *ssp); void synchronize_srcu(struct srcu_struct *ssp); +/** + * srcu_readers_active - returns true if there are readers, and false otherwise + * @ssp: which srcu_struct to count active readers (holding srcu_read_lock). + * + * Note that this is not an atomic primitive, and can therefore suffer + * severe errors when invoked on an active srcu_struct. That said, it can be + * useful as an error check at cleanup time. + */ +static inline bool srcu_readers_active(struct srcu_struct *ssp) +{ +#ifdef CONFIG_TINY_SRCU + return READ_ONCE(ssp->srcu_lock_nesting[0]) || READ_ONCE(ssp->srcu_lock_nesting[1]); +#else + int cpu; + unsigned long sum = 0; + + for_each_possible_cpu(cpu) { + struct srcu_data *sdp = per_cpu_ptr(ssp->sda, cpu); + + sum += atomic_long_read(&sdp->srcu_ctrs[0].srcu_locks); + sum += atomic_long_read(&sdp->srcu_ctrs[1].srcu_locks); + sum -= atomic_long_read(&sdp->srcu_ctrs[0].srcu_unlocks); + sum -= atomic_long_read(&sdp->srcu_ctrs[1].srcu_unlocks); + } + + return sum; +#endif +} + #define SRCU_GET_STATE_COMPLETED 0x1 /** diff --git a/kernel/rcu/srcutiny.c b/kernel/rcu/srcutiny.c index a2e2d516e51b..5dc26af604bf 100644 --- a/kernel/rcu/srcutiny.c +++ b/kernel/rcu/srcutiny.c @@ -85,7 +85,7 @@ EXPORT_SYMBOL_GPL(init_srcu_struct); */ void cleanup_srcu_struct(struct srcu_struct *ssp) { - WARN_ON(ssp->srcu_lock_nesting[0] || ssp->srcu_lock_nesting[1]); + WARN_ON(srcu_readers_active(ssp)); irq_work_sync(&ssp->srcu_irq_work); flush_work(&ssp->srcu_work); WARN_ON(ssp->srcu_gp_running); diff --git a/kernel/rcu/srcutree.c b/kernel/rcu/srcutree.c index 0d01cd8c4b4a..b1e97ba2e53f 100644 --- a/kernel/rcu/srcutree.c +++ b/kernel/rcu/srcutree.c @@ -598,31 +598,6 @@ static bool srcu_readers_active_idx_check(struct srcu_struct *ssp, int idx) return srcu_readers_lock_idx(ssp, idx, did_gp, unlocks); } -/** - * srcu_readers_active - returns true if there are readers. and false - * otherwise - * @ssp: which srcu_struct to count active readers (holding srcu_read_lock). - * - * Note that this is not an atomic primitive, and can therefore suffer - * severe errors when invoked on an active srcu_struct. That said, it - * can be useful as an error check at cleanup time. - */ -static bool srcu_readers_active(struct srcu_struct *ssp) -{ - int cpu; - unsigned long sum = 0; - - for_each_possible_cpu(cpu) { - struct srcu_data *sdp = per_cpu_ptr(ssp->sda, cpu); - - sum += atomic_long_read(&sdp->srcu_ctrs[0].srcu_locks); - sum += atomic_long_read(&sdp->srcu_ctrs[1].srcu_locks); - sum -= atomic_long_read(&sdp->srcu_ctrs[0].srcu_unlocks); - sum -= atomic_long_read(&sdp->srcu_ctrs[1].srcu_unlocks); - } - return sum; -} - /* * We use an adaptive strategy for synchronize_srcu() and especially for * synchronize_srcu_expedited(). We spin for a fixed time period diff --git a/rust/helpers/srcu.c b/rust/helpers/srcu.c index 79dd24a104ef..fa4b5879dda5 100644 --- a/rust/helpers/srcu.c +++ b/rust/helpers/srcu.c @@ -13,6 +13,11 @@ __rust_helper int rust_helper_init_srcu_struct_with_key(struct srcu_struct *ssp, #endif /* CONFIG_DEBUG_LOCK_ALLOC */ } +__rust_helper bool rust_helper_srcu_readers_active(struct srcu_struct *ssp) +{ + return srcu_readers_active(ssp); +} + __rust_helper int rust_helper_srcu_read_lock(struct srcu_struct *ssp) { return srcu_read_lock(ssp); -- 2.51.2