From nobody Sat Mar 08 08:13:55 2025 X-Original-To: dev-commits-src-branches@mlmmj.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mlmmj.nyi.freebsd.org (Postfix) with ESMTP id 4Z8wsd0XCkz5qcyQ; Sat, 08 Mar 2025 08:13:57 +0000 (UTC) (envelope-from git@FreeBSD.org) Received: from mxrelay.nyi.freebsd.org (mxrelay.nyi.freebsd.org [IPv6:2610:1c1:1:606c::19:3]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256 client-signature RSA-PSS (4096 bits) client-digest SHA256) (Client CN "mxrelay.nyi.freebsd.org", Issuer "R10" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 4Z8wsc0p47z3kwt; Sat, 08 Mar 2025 08:13:56 +0000 (UTC) (envelope-from git@FreeBSD.org) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=freebsd.org; s=dkim; t=1741421636; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding; bh=Ao9TxHY4KObzEG4skGeM0ZX7PUwZWlS+A49aOnEaD4M=; b=ljYndE4WWU7Ml5KbRrwt9ge3ZhGCcp30x3T2cfcefvYTSwlXrWme0qllh4biv8UiMw5pmI yHIYEPr8zf5jLaSss1UGDM7/5L3KJYbP5aFRALJrlW0pFKiSfOlTU+ekdmPBl7N/t5bL2q BokNmZhV4Dcl2QKisJ2G3Aw5CZq7OEkNIWNsoAVxs9Xbfq4A2yA0lVhlsIhrwtkzpnlo4H An9r8zkFPMyc2D25Nj30qtwMQFkMNsjJR7tYSjJ8sNCMyxKOTzlvgtRnBVC0+SGsv2UMf7 eK29sss29A0i1rViAiw7TJ3qjNSRE5e3QwVDZ84e1ZSHG7nApnmvJKd3hR24fQ== ARC-Seal: i=1; s=dkim; d=freebsd.org; t=1741421636; a=rsa-sha256; cv=none; b=irT7bZytvZFEfvO4maY/ysxEJRGwS5wWq8XOyIoyXUcD0z7+LWMdkr6jGnNNMH78QZSFbd bJIvnjUJDfgmkeA2YKIzxUWUKZGYob4SO95t9jprxN7+bkV26ImODcL5XE2yQsJbv4t4w1 HgcAN6U6pef6TikyydRHiBno+qukkSo4MTNv7S2NJNqhYsUeaw8UufD3oY6SjB7V1zE6Ej JVceEsKBwkgbz35PF/JBirEkm75AKeTwqXwEjXUp8C8VvHv1rLFu2n8zN0JBOZLSyF3LXC 0JBEwgIlpMhiGNKOhiFJpEVw1YZvcuk8bAZD/OywyshS0qKkT8fWZ1he0Mzizw== ARC-Authentication-Results: i=1; mx1.freebsd.org; none ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=freebsd.org; s=dkim; t=1741421636; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding; bh=Ao9TxHY4KObzEG4skGeM0ZX7PUwZWlS+A49aOnEaD4M=; b=aOpqATLTybVovAb194bfeml3fLw5xNBDsxKNT+GwVzWdKpJT8GsXdYu9C9y3RGc7afSJne DvDgkkECbhl+R2AQSfd12jfG6CJvLubA0MqNE7Spdatvaj6I9Egb2JR17gu4zN12ND9edL DtI9vAXe/9Zi0isNcYDlTGv3RFQMHn68dXO/TA28w55guvuYvpID0oSI4tMz+vgT/qWQbR sUEOn89A3ufQLy0Hf4qxUG6NgktQN8L48/eqUMjyUmf7C+Xw4X3sKpVwoNZyWFnYVkrrG/ qRPa0DM8UwzkbSC7PoWWEyadeVItpt5EWcz5EwvePm9DKodb/4UW0zCEzU6QDg== Received: from gitrepo.freebsd.org (gitrepo.freebsd.org [IPv6:2610:1c1:1:6068::e6a:5]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (Client did not present a certificate) by mxrelay.nyi.freebsd.org (Postfix) with ESMTPS id 4Z8wsc0MfHzjD; Sat, 08 Mar 2025 08:13:56 +0000 (UTC) (envelope-from git@FreeBSD.org) Received: from gitrepo.freebsd.org ([127.0.1.44]) by gitrepo.freebsd.org (8.18.1/8.18.1) with ESMTP id 5288DtEk097611; Sat, 8 Mar 2025 08:13:55 GMT (envelope-from git@gitrepo.freebsd.org) Received: (from git@localhost) by gitrepo.freebsd.org (8.18.1/8.18.1/Submit) id 5288DtbP097608; Sat, 8 Mar 2025 08:13:55 GMT (envelope-from git) Date: Sat, 8 Mar 2025 08:13:55 GMT Message-Id: <202503080813.5288DtbP097608@gitrepo.freebsd.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-branches@FreeBSD.org From: Mark Johnston Subject: git: ffb4d077710a - stable/14 - ktr: Use STAILQ_EMPTY_ATOMIC when checking for records in ktr_drain() List-Id: Commits to the stable branches of the FreeBSD src repository List-Archive: https://lists.freebsd.org/archives/dev-commits-src-branches List-Help: List-Post: List-Subscribe: List-Unsubscribe: X-BeenThere: dev-commits-src-branches@freebsd.org Sender: owner-dev-commits-src-branches@FreeBSD.org MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit X-Git-Committer: markj X-Git-Repository: src X-Git-Refname: refs/heads/stable/14 X-Git-Reftype: branch X-Git-Commit: ffb4d077710ae1a61dabc362b0963fc62642f0c9 Auto-Submitted: auto-generated The branch stable/14 has been updated by markj: URL: https://cgit.FreeBSD.org/src/commit/?id=ffb4d077710ae1a61dabc362b0963fc62642f0c9 commit ffb4d077710ae1a61dabc362b0963fc62642f0c9 Author: Mark Johnston AuthorDate: 2025-02-14 15:49:27 +0000 Commit: Mark Johnston CommitDate: 2025-03-07 22:51:48 +0000 ktr: Use STAILQ_EMPTY_ATOMIC when checking for records in ktr_drain() This is an unlocked check, and after commit 34740937f7a4 the debug checks in STAILQ_EMPTY may spuriously fail here. In particular, the per process queue is updated under the global ktrace mutex, not held in ktr_drain(). If a record is enqueued concurrently, the recording thread will schedule an AST to drain the queue again, so it should not be possible for a race to leave records in the queue indefinitely. Reviewed by: kib, olce Reported by: syzbot+d67eddd8c4923ee28bb7@syzkaller.appspotmail.com MFC after: 2 weeks Fixes: 34740937f7a4 ("queue: New debug macros for STAILQ") Differential Revision: https://reviews.freebsd.org/D48899 (cherry picked from commit 36631977d8c9264b7a54f039289918adea4d2a03) --- sys/kern/kern_ktrace.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/sys/kern/kern_ktrace.c b/sys/kern/kern_ktrace.c index 2b311f2d36dc..3d3cbbd29c6f 100644 --- a/sys/kern/kern_ktrace.c +++ b/sys/kern/kern_ktrace.c @@ -396,7 +396,7 @@ ktr_drain(struct thread *td) STAILQ_INIT(&local_queue); - if (!STAILQ_EMPTY(&td->td_proc->p_ktr)) { + if (!STAILQ_EMPTY_ATOMIC(&td->td_proc->p_ktr)) { mtx_lock(&ktrace_mtx); STAILQ_CONCAT(&local_queue, &td->td_proc->p_ktr); mtx_unlock(&ktrace_mtx);