From patchwork Mon Jul 1 22:39:32 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andrii Nakryiko X-Patchwork-Id: 13718694 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 B15C3171E4B; Mon, 1 Jul 2024 22:40:08 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1719873608; cv=none; b=g4bXbOtLbmYUvp8ox+5p2Ag4r9ZSRZMn9BOCAtyo31GriSDVL0oU6lGv2pUVGQBz6lEC25BnnU2L23QDjbQOBo5S68oPWq3pnPCAGXolkP37aur+y2ecicJ1l2zk6Ob6W5yBoGFbu6k0l9yuXkvPq0sJSiBs9CD8BbYEKHytM7w= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1719873608; c=relaxed/simple; bh=I4Eo38mmIesrQ77ZzSoxqm6W+ydpRlm53vqTuFQpouQ=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=e3wkez4hkdD2zdeXxs06EFkEdlh3FNxfu9c+ptLBULQaQW/hZNztW9pDtHaSqMI2bxV86f+jifSHxlAK7ZcWLuMJ2xYfLpR0dEiPmRoMsJbicCIpDYJrC5unOeFcE9NpFUSMrdMwpFCV95twRnB2MqBdCTfQfUgqmhYHfkHfpAI= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=ilFO+4rL; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="ilFO+4rL" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 66BC4C116B1; Mon, 1 Jul 2024 22:40:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1719873608; bh=I4Eo38mmIesrQ77ZzSoxqm6W+ydpRlm53vqTuFQpouQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ilFO+4rL4icjqX3iDeTY8fJcAvtkaeDOkCED6DAqKE3373rc/DwoIga39QBGcKV43 kxZmhV4SL7eqOitpwmegIIy2D9N2oEMfEBFYCyHdLk4TBgtU4dx2jXmzPttYaD6P3c W/sMaJfH0iJqObgr9DS1FPciUGAeBABYNRJgngsSkeyCOR8uX+46LDvY44clTm7hyy 8hgT3/4OXE2uPhJ0ebiDG6T1InmpGsGBWW8p+1O3287srHrQ+b6etUhjmeQFrhgLgR GhvDgZKNxI0t16InlzlR0uw9aont3bS1QauVB6s/pF6fPyRWMGzEbv9KFcQUdUXCpp MvpmsKH8g1Gwg== From: Andrii Nakryiko To: linux-trace-kernel@vger.kernel.org, rostedt@goodmis.org, mhiramat@kernel.org, oleg@redhat.com Cc: peterz@infradead.org, mingo@redhat.com, bpf@vger.kernel.org, jolsa@kernel.org, paulmck@kernel.org, clm@meta.com, Andrii Nakryiko Subject: [PATCH v2 09/12] uprobes: batch uprobes_treelock during registration Date: Mon, 1 Jul 2024 15:39:32 -0700 Message-ID: <20240701223935.3783951-10-andrii@kernel.org> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20240701223935.3783951-1-andrii@kernel.org> References: <20240701223935.3783951-1-andrii@kernel.org> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Now that we have a good separate of each registration step, take uprobes_treelock just once for relevant registration step, and then process all relevant uprobes in one go. Even if writer lock introduces a relatively large delay (as might happen with per-CPU RW semaphore), this will keep overall batch attachment reasonably fast. We teach put_uprobe(), though __put_uprobe() helper, to optionally take or not uprobes_treelock, to accommodate this pattern. With these changes we don't need insert_uprobe() operation that unconditionally takes uprobes_treelock, so get rid of it, leaving only lower-level __insert_uprobe() helper. Signed-off-by: Andrii Nakryiko --- kernel/events/uprobes.c | 45 +++++++++++++++++++++-------------------- 1 file changed, 23 insertions(+), 22 deletions(-) diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c index 128677ffe662..ced85284bbf4 100644 --- a/kernel/events/uprobes.c +++ b/kernel/events/uprobes.c @@ -665,7 +665,7 @@ static void uprobe_free_rcu(struct rcu_head *rcu) kfree(uprobe); } -static void put_uprobe(struct uprobe *uprobe) +static void __put_uprobe(struct uprobe *uprobe, bool tree_locked) { s64 v; @@ -683,7 +683,8 @@ static void put_uprobe(struct uprobe *uprobe) if (unlikely((u32)v == 0)) { bool destroy; - write_lock(&uprobes_treelock); + if (!tree_locked) + write_lock(&uprobes_treelock); /* * We might race with find_uprobe()->__get_uprobe() executed * from inside read-locked uprobes_treelock, which can bump @@ -706,7 +707,8 @@ static void put_uprobe(struct uprobe *uprobe) destroy = atomic64_read(&uprobe->ref) == v; if (destroy && uprobe_is_active(uprobe)) rb_erase(&uprobe->rb_node, &uprobes_tree); - write_unlock(&uprobes_treelock); + if (!tree_locked) + write_unlock(&uprobes_treelock); /* * Beyond here we don't need RCU protection, we are either the @@ -745,6 +747,11 @@ static void put_uprobe(struct uprobe *uprobe) rcu_read_unlock_trace(); } +static void put_uprobe(struct uprobe *uprobe) +{ + __put_uprobe(uprobe, false); +} + static __always_inline int uprobe_cmp(const struct inode *l_inode, const loff_t l_offset, const struct uprobe *r) @@ -844,21 +851,6 @@ static struct uprobe *__insert_uprobe(struct uprobe *uprobe) return u; } -/* - * Acquire uprobes_treelock and insert uprobe into uprobes_tree - * (or reuse existing one, see __insert_uprobe() comments above). - */ -static struct uprobe *insert_uprobe(struct uprobe *uprobe) -{ - struct uprobe *u; - - write_lock(&uprobes_treelock); - u = __insert_uprobe(uprobe); - write_unlock(&uprobes_treelock); - - return u; -} - static void ref_ctr_mismatch_warn(struct uprobe *cur_uprobe, struct uprobe *uprobe) { @@ -1318,6 +1310,8 @@ int uprobe_register_batch(struct inode *inode, int cnt, uc->uprobe = uprobe; } + ret = 0; + write_lock(&uprobes_treelock); for (i = 0; i < cnt; i++) { struct uprobe *cur_uprobe; @@ -1325,19 +1319,24 @@ int uprobe_register_batch(struct inode *inode, int cnt, uprobe = uc->uprobe; /* add to uprobes_tree, sorted on inode:offset */ - cur_uprobe = insert_uprobe(uprobe); + cur_uprobe = __insert_uprobe(uprobe); /* a uprobe exists for this inode:offset combination */ if (cur_uprobe != uprobe) { if (cur_uprobe->ref_ctr_offset != uprobe->ref_ctr_offset) { ref_ctr_mismatch_warn(cur_uprobe, uprobe); - put_uprobe(cur_uprobe); + + __put_uprobe(cur_uprobe, true); ret = -EINVAL; - goto cleanup_uprobes; + goto unlock_treelock; } kfree(uprobe); uc->uprobe = cur_uprobe; } } +unlock_treelock: + write_unlock(&uprobes_treelock); + if (ret) + goto cleanup_uprobes; for (i = 0; i < cnt; i++) { uc = get_uprobe_consumer(i, ctx); @@ -1367,13 +1366,15 @@ int uprobe_register_batch(struct inode *inode, int cnt, } cleanup_uprobes: /* put all the successfully allocated/reused uprobes */ + write_lock(&uprobes_treelock); for (i = 0; i < cnt; i++) { uc = get_uprobe_consumer(i, ctx); if (uc->uprobe) - put_uprobe(uc->uprobe); + __put_uprobe(uc->uprobe, true); uc->uprobe = NULL; } + write_unlock(&uprobes_treelock); return ret; }