From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mta0.migadu.com (out-219.mta0.migadu.com [91.218.175.219]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id CE6C03368A5 for ; Wed, 19 Aug 2026 18:15:54 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.219 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787163358; cv=none; b=RlDsIhnPS2NN4Kcd/DtmQD4F813tzlGaMPtU0Cy+WZFf5sfET2LHQcWCoqwzHMzbYXS5I8MFohk5+OZ7lrPApq4bPlVBnpquCo+W5miS3dAcBPeGSznPBC/c70q63y9STNfo8t9vNCkIyRiCU5BEhBEPH/qZ9uAg/FwDgjJ8vPo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787163358; c=relaxed/simple; bh=m+TzzdLhvhVJB2lB9VhzD3jOjcpTXoU6s5EqQxRV40w=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=nuF1ylrfmf/6eMYOpRuuGDjdLBJ71X75gCswo8g4kLP/zqylqzBNycPWKiWe0GLhMOY2I/+ztVwibhmrrVz9iK422igBB8qpmah4ivrwI7/Hp3ukeRAlGQdDHSKDSUWWtaJUlI39bMru8A89Q2ID20a4aLUJA6cQgW0G0DZY+iM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=P8tL/xfm; arc=none smtp.client-ip=91.218.175.219 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="P8tL/xfm" X-Envelope-To: linux-kernel@vger.kernel.org DKIM-Signature: a=rsa-sha256; bh=m+TzzdLhvhVJB2lB9VhzD3jOjcpTXoU6s5EqQxRV40w=; c=simple/simple; d=linux.dev; h=from:to:subject:date:message-id:mime-version:content-type; s=key1; t=1787163352; v=1; x=1787768152; b=P8tL/xfmTVKjCmI4rr53uVkWVyCxLF7dsjNLufMsKIf9eCc7sipV4MHrD7O+7ZJRhhOCX/e2 0dvDgW2mHYglFNbxaqBVdhBy+uXBe8FdOFqOhhE85ku47pYjMl+nM2Ylk/EePMZoBey0NknDIqU e0tL9oRGCZvsMVPvLYKbpk/M= X-Envelope-To: linux-kernel@vger.kernel.org Received: from localhost.localdomain (180.165.15.98) by mta12.migadu.com with ESMTPS id 85814f8730efd461; Wed, 19 Aug 2026 18:15:52 +0000 X-Mizu-Trace-ID: 85814f8730efd461 X-Migadu-Flow: FLOW_OUT From: wen.yang@linux.dev To: Gabriele Monaco Cc: Nam Cao , linux-trace-kernel@vger.kernel.org, linux-kernel@vger.kernel.org, Wen Yang Subject: [PATCH v5 1/9] rv: Introduce DA_MON_ALLOCATION_STRATEGY Date: Thu, 20 Aug 2026 02:15:18 +0800 Message-Id: <60632bdb34707ffde64381549f1ce09118bd8f5f.1787161646.git.wen.yang@linux.dev> X-Mailer: git-send-email 2.25.1 In-Reply-To: References: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Wen Yang Per-object DA storage allocation is currently limited to kmalloc on demand. Add a compile-time selector so monitors can choose among three strategies: DA_ALLOC_AUTO (default) - kmalloc per object on the monitor path DA_ALLOC_POOL - pre-allocated fixed-size mempool; selected by defining DA_MON_POOL_SIZE DA_ALLOC_MANUAL - caller pre-inserts storage; framework only links the target field Suggested-by: Gabriele Monaco Signed-off-by: Wen Yang --- include/rv/da_monitor.h | 140 ++++++++++++++++++++++++++++++++++++++-- 1 file changed, 133 insertions(+), 7 deletions(-) diff --git a/include/rv/da_monitor.h b/include/rv/da_monitor.h index e3cf85c9ce55..48c534324cbb 100644 --- a/include/rv/da_monitor.h +++ b/include/rv/da_monitor.h @@ -14,7 +14,50 @@ #ifndef _RV_DA_MONITOR_H #define _RV_DA_MONITOR_H +/* + * Allocation strategies for RV_MON_PER_OBJ monitors, selected by defining + * one of the following before including this header (never both): + * + * DA_MON_POOL_SIZE N - pool mode, N pre-allocated slots + * DA_MON_ALLOCATION_STRATEGY - explicit strategy (see below) + * (neither) - auto mode (default) + * + * DA_ALLOC_AUTO - kmalloc on demand; unbounded. + * DA_ALLOC_POOL - pre-allocated fixed-size pool. + * DA_ALLOC_MANUAL - caller pre-inserts storage; framework links the target. + */ +#define DA_ALLOC_AUTO 0 +#define DA_ALLOC_POOL 1 +#define DA_ALLOC_MANUAL 2 + +#ifdef DA_MON_POOL_SIZE +#ifdef DA_MON_ALLOCATION_STRATEGY +#error "Define only one of DA_MON_POOL_SIZE or DA_MON_ALLOCATION_STRATEGY" +#endif +#if DA_MON_POOL_SIZE == 0 +#error "DA_MON_POOL_SIZE must be non-zero" +#endif +#define DA_MON_ALLOCATION_STRATEGY DA_ALLOC_POOL +#endif /* DA_MON_POOL_SIZE */ + +#ifndef DA_MON_ALLOCATION_STRATEGY +#ifdef DA_SKIP_AUTO_ALLOC +#define DA_MON_ALLOCATION_STRATEGY DA_ALLOC_MANUAL +#else +#define DA_MON_ALLOCATION_STRATEGY DA_ALLOC_AUTO +#endif +#endif /* DA_MON_ALLOCATION_STRATEGY */ + +/* Zero default keeps pool-mode conditionals compile-time constant. */ +#ifndef DA_MON_POOL_SIZE +#if DA_MON_ALLOCATION_STRATEGY == DA_ALLOC_POOL +#error "DA_ALLOC_POOL requires DA_MON_POOL_SIZE to be defined and non-zero" +#endif +#define DA_MON_POOL_SIZE 0 +#endif /* DA_MON_POOL_SIZE */ + #include +#include #include #include #include @@ -67,6 +110,16 @@ static struct rv_monitor rv_this; #define da_monitor_sync_hook() #endif +/* + * Per-object teardown hook, called after da_monitor_reset_all() + + * da_monitor_sync_hook() and before hash_del_rcu() for each entry. + * All HA timer callbacks have completed at this point. + * Define before including this header. Default: no-op. + */ +#ifndef da_extra_cleanup +#define da_extra_cleanup(da_mon) +#endif + /* * Type for the target id, default to int but can be overridden. * A long type can work as hash table key (PER_OBJ) but will be downgraded to @@ -543,6 +596,59 @@ static inline monitor_target da_get_target_by_id(da_id_type id) return mon_storage->target; } +/* + * Pre-allocated mempool for DA_ALLOC_POOL monitors: DA_MON_POOL_SIZE + * slots, eager-allocated at init. mempool_alloc_preallocated() pops a + * slot without touching the allocator (bounded start latency; NULL when + * exhausted). mempool_free() is safe from RCU-callback context. + * Non-pool monitors get a zero-initialised mempool_t; pool paths compile + * away. + */ +static mempool_t da_monitor_pool; + +static void da_pool_return_cb(struct rcu_head *head) +{ + struct da_monitor_storage *ms = + container_of(head, struct da_monitor_storage, rcu); + + mempool_free(ms, &da_monitor_pool); +} + +/* + * da_create_pool_storage - pop a free pool slot and insert it into the hash. + * + * Returns the new da_monitor, or NULL if the pool is exhausted. Finding + * an existing entry for the same id fires WARN_ON_ONCE (double-start bug). + * + * Caller must hold an RCU read-side CS and the monitor's serialisation lock. + */ +static inline struct da_monitor * +da_create_pool_storage(da_id_type id, monitor_target target, + struct da_monitor *da_mon) +{ + struct da_monitor_storage *mon_storage, *existing; + + if (da_mon) + return da_mon; + + mon_storage = mempool_alloc_preallocated(&da_monitor_pool); + if (!mon_storage) + return NULL; + memset(mon_storage, 0, sizeof(*mon_storage)); + + mon_storage->id = id; + mon_storage->target = target; + + /* Single consumer under the caller's lock; duplicate is a double-start bug. */ + existing = __da_get_mon_storage(id); + if (WARN_ON_ONCE(existing)) { + mempool_free(mon_storage, &da_monitor_pool); + return NULL; + } + hash_add_rcu(da_monitor_ht, &mon_storage->node, id); + return &mon_storage->rv.da_mon; +} + /* * da_destroy_storage - destroy the per-object storage * @@ -564,7 +670,10 @@ static inline void da_destroy_storage(da_id_type id) return; da_monitor_reset_hook(&mon_storage->rv.da_mon); hash_del_rcu(&mon_storage->node); - kfree_rcu(mon_storage, rcu); + if (DA_MON_ALLOCATION_STRATEGY == DA_ALLOC_POOL) + call_rcu(&mon_storage->rcu, da_pool_return_cb); + else + kfree_rcu(mon_storage, rcu); } static void __da_monitor_reset_all(void (*reset)(struct da_monitor *)) @@ -590,6 +699,9 @@ static inline void da_monitor_reset_state_all(void) static inline int da_monitor_init(void) { hash_init(da_monitor_ht); + if (DA_MON_ALLOCATION_STRATEGY == DA_ALLOC_POOL) + return mempool_init_kmalloc_pool(&da_monitor_pool, DA_MON_POOL_SIZE, + sizeof(struct da_monitor_storage)); return 0; } @@ -607,8 +719,17 @@ static inline void da_monitor_destroy(void) * pending, we can safely assume no concurrent user. */ hash_for_each_safe(da_monitor_ht, bkt, tmp, mon_storage, node) { + da_extra_cleanup(&mon_storage->rv.da_mon); hash_del_rcu(&mon_storage->node); - kfree(mon_storage); + if (DA_MON_ALLOCATION_STRATEGY == DA_ALLOC_POOL) + mempool_free(mon_storage, &da_monitor_pool); + else + kfree(mon_storage); + } + + if (DA_MON_ALLOCATION_STRATEGY == DA_ALLOC_POOL) { + rcu_barrier(); + mempool_exit(&da_monitor_pool); } } @@ -617,11 +738,16 @@ static inline void da_monitor_destroy(void) * start condition is in a context problematic for allocation (e.g. scheduling). * In such case, if the storage was pre-allocated without a target, set it now. */ -#ifdef DA_SKIP_AUTO_ALLOC -#define da_prepare_storage da_fill_empty_storage -#else -#define da_prepare_storage da_create_storage -#endif /* DA_SKIP_AUTO_ALLOC */ +static inline struct da_monitor * +da_prepare_storage(da_id_type id, monitor_target target, + struct da_monitor *da_mon) +{ + if (DA_MON_ALLOCATION_STRATEGY == DA_ALLOC_POOL) + return da_create_pool_storage(id, target, da_mon); + if (DA_MON_ALLOCATION_STRATEGY == DA_ALLOC_MANUAL) + return da_fill_empty_storage(id, target, da_mon); + return da_create_storage(id, target, da_mon); +} #endif /* RV_MON_TYPE */ -- 2.25.1