From nobody Fri Feb 14 15:56:46 2025 X-Original-To: dev-commits-src-main@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 4Yvc9q0f01z5nHvd; Fri, 14 Feb 2025 15:56:47 +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 "R11" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 4Yvc9q02Rmz3SZd; Fri, 14 Feb 2025 15:56:47 +0000 (UTC) (envelope-from git@FreeBSD.org) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=freebsd.org; s=dkim; t=1739548607; 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=piJ5Ja2MjEx1WsIKbHRI9PfbEN40UP8crNvRBv22dW8=; b=eYqGy9g4E2MOUv0ZDAYi+/MizNL0LVLzPEbyj/e6qYYpBwFfVWK1zBSVHEy5LJF3q+Ca4c IHXcwwSuKFQip3ACC9zj54wMsr5Mdp9vuMp69OCLwoGwtC++kzxUDDkc6m7/xG1ci6607b uvPnMSyIKUG/neP5vj8aO7ger1fTUY6CpZ54CH4pWSfDXshLrjYNd1D7uT/wVDFDNm9xH6 IlZY/1K9iEnOQJhnU1bLc8zlihWGnhlV3NyOzK8dm0E/GAmlyPR78SpK6yuKY+bCMWSLB6 /L9X/9DATmH5o5yzZCU4S8UHaV15OwFO4JahNkktdTsl8oobej826iGnrgMlXQ== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=freebsd.org; s=dkim; t=1739548607; 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=piJ5Ja2MjEx1WsIKbHRI9PfbEN40UP8crNvRBv22dW8=; b=WVoySkWbghJF8lgh5f+RiGU+mWKE/NsVuQtVQm057DYO5BSkMwEZwc0J+Em7GEb+fZ8Vt9 yNHKXXoUjGMWhZ+QJNCNIf7vFGko2ZlE/H9MVOeQJI17gL84Z6E3P12YxjrwkNLlIjJa99 E5SeP1jCxFXrX0U85yplcSu5S7WLiDb4Ctu8rikr4xi3kH/SI8ls9hxLRGtWNs8S+toMb8 w7kouJkZv3Byv/bkDuQyRkmsv+lOK92uM8ad6DJA4tXy/Hs+fmtleZKiEPXNL4q4BYVDrM GB3IPQKADNlA+/UNpQJ1v6Hc6cJqBQsGGE1OXqHX5g7Nt4Zk37zbDBSq4Eh7BQ== ARC-Seal: i=1; s=dkim; d=freebsd.org; t=1739548607; a=rsa-sha256; cv=none; b=IxQbu7hhoavW66wY1kv+JfJzBkHi7mDQZtddNhuKiXe/gm+Jytmtgp/v+RualETP6X48x/ dGMZ15db9RCCvHFXA0lGG7MUYDknD3HAayJcIIGX1vRaCtFdQJPtzZn0I6anIfP7N12bBB rtP4sGuR4XIxMIikPeR6E/2bkcDK2J5lr1CMUoFd6kdsvUBetGLfot5Ad1Vh1kZm7K+OOn Okj2wnS5VDjVdDsBO7bWpQmhOjucUWv3Wz4jDOUsANDxNii1tcZLV8hcbs3uhJ19IO1oy3 EjCp2YCju4MHXZy3SvBckSvepJqixuxAoztCjWu7OqwRDnw5wYVhxT+HyCTrcw== ARC-Authentication-Results: i=1; mx1.freebsd.org; none 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 4Yvc9p6ldwzdc0; Fri, 14 Feb 2025 15:56:46 +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 51EFukfM046188; Fri, 14 Feb 2025 15:56:46 GMT (envelope-from git@gitrepo.freebsd.org) Received: (from git@localhost) by gitrepo.freebsd.org (8.18.1/8.18.1/Submit) id 51EFukh4046185; Fri, 14 Feb 2025 15:56:46 GMT (envelope-from git) Date: Fri, 14 Feb 2025 15:56:46 GMT Message-Id: <202502141556.51EFukh4046185@gitrepo.freebsd.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-main@FreeBSD.org From: Mark Johnston Subject: git: 36631977d8c9 - main - ktr: Use STAILQ_EMPTY_ATOMIC when checking for records in ktr_drain() List-Id: Commit messages for the main branch of the src repository List-Archive: https://lists.freebsd.org/archives/dev-commits-src-main List-Help: List-Post: List-Subscribe: List-Unsubscribe: X-BeenThere: dev-commits-src-main@freebsd.org Sender: owner-dev-commits-src-main@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/main X-Git-Reftype: branch X-Git-Commit: 36631977d8c9264b7a54f039289918adea4d2a03 Auto-Submitted: auto-generated The branch main has been updated by markj: URL: https://cgit.FreeBSD.org/src/commit/?id=36631977d8c9264b7a54f039289918adea4d2a03 commit 36631977d8c9264b7a54f039289918adea4d2a03 Author: Mark Johnston AuthorDate: 2025-02-14 15:49:27 +0000 Commit: Mark Johnston CommitDate: 2025-02-14 15:52:29 +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 --- 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 a67b773a154c..7a5846de9f6a 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);