From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 E317B3B7B7B; Fri, 4 Sep 2026 05:18:17 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788499099; cv=none; b=la+jTeKd/3TY1bcizgS4MU3gr0PdWHWH0FTi8DeRKeuIpSU4sFluzFsWzDQfXYdubFtaAL4tLiL3MNv1Xq1I5XyeGdgxoshZ8iFCyYdEn9zAxd1Fa9RJxqpCvS2iCI6kLT5uKUoV2CS9mQkapIFlax8d09TV8AxZRb6jF0qidC0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788499099; c=relaxed/simple; bh=ZvtakKzAHqdT47gk8fA+0WgXXeHDpTG/97ZiylvbtpI=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=RV66MDSwCgnmZuGB8wyerFqlfRNEjZb3L20uKR/zSlUX8NhnDgemorgjlKeytPNroEmckjZjtAmYrcIL+4K5epU/7Re86dWEIqEc2+yME5q29PkGvzpJtRD2QFA53FlGvogZXQmmIKv1bUqeIfPbwpw8x/YlZ98P4oJ6yUBbNDY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=W6BO3tkf; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="W6BO3tkf" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 46D0C1F0155E; Fri, 4 Sep 2026 05:18:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1788499097; bh=YsL1DLOVgipS7vDwLqYBc7mkFKg9LHE7UUPJ3vzlwss=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=W6BO3tkfi9XIf+G4B76AGAV6Krl4QLZZFSmvcZUoy5zxe4w9ckatsnbAeTY6nCeQB desZKaaMRNnkVtl2zocw7LNeUEFBhBq/x5GMK/NmZrp9AqpcQ/WWlATUtE6CII5Nr+ 55dwV80t/ZJQjParta4ffHVkB31BWHdfauzVp/Mk= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Sashiko , Terry Bowman , Dave Jiang , Jonathan Cameron , Tony Luck Subject: [PATCH 7.2 296/713] acpi/apei/ghes: Use raw_spinlock_t for CXL CPER work locks Date: Fri, 4 Sep 2026 06:54:24 +0200 Message-ID: <20260904045810.476310406@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260904045803.810145556@linuxfoundation.org> References: <20260904045803.810145556@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 7.2-stable review patch. If anyone has any objections, please let me know. ------------------ From: Terry Bowman commit 6625ca499c3131ef63be3215f8f942d7a097ea3a upstream. The CXL CPER work registration and unregistration helpers acquire cxl_cper_work_lock and cxl_cper_prot_err_work_lock with a spinlock guard(), which leaves local interrupts enabled. The corresponding post paths (cxl_cper_post_event(), cxl_cper_post_prot_err()) execute in hard IRQ context (they are called from the GHES error notification path) and acquire the same locks with an irqsave guard(). If a CPU is holding one of these locks via a spinlock guard() when a GHES interrupt arrives on the same CPU, the IRQ handler spins on the held lock waiting for it to release, while the lock holder is preempted by the IRQ. The result is a deadlock. Convert both locks from spinlock_t to raw_spinlock_t and use guard() at all call sites. On PREEMPT_RT kernels spinlock_t is backed by rt_mutex and sleeping from hard IRQ context is not permitted; raw_spinlock_t is safe in both contexts. Add WARN_ONCE to both register functions to surface double-registration bugs at runtime. Restructure both unregister functions to clear the global work pointer under the lock before calling cancel_work_sync(), closing the window where a CPER interrupt could schedule work on a pointer about to be freed. Add kfifo_reset() after cancel_work_sync() so stale entries are not replayed on next module load. Both kfifos are single-consumer: only one work_struct is registered at a time, enforced by the WARN_ONCE guard in the register functions. kfifo_reset() is safe outside the lock because cancel_work_sync() has already quiesced the consumer, and no new consumer can register until the current module exit completes and a fresh module init runs. Remove the redundant cancel_work_sync() call from cxl_ras_exit() and cxl_pci_driver_exit(). The CPER unregister functions now quiesce the work internally. Reported-by: Sashiko Signed-off-by: Terry Bowman Fixes: 5e4a264bf8b5 ("acpi/ghes: Process CXL Component Events") Fixes: 36f257e3b0ba ("acpi/ghes, cxl/pci: Process CXL CPER Protocol Errors") Cc: stable@vger.kernel.org Reviewed-by: Dave Jiang Reviewed-by: Jonathan Cameron Reviewed-by: Tony Luck Link: https://patch.msgid.link/20260803221810.3685703-4-terry.bowman@amd.com Signed-off-by: Dave Jiang Signed-off-by: Greg Kroah-Hartman --- drivers/acpi/apei/ghes.c | 50 +++++++++++++++++++++++++++++++---------------- drivers/cxl/core/ras.c | 1 drivers/cxl/pci.c | 1 3 files changed, 33 insertions(+), 19 deletions(-) --- a/drivers/acpi/apei/ghes.c +++ b/drivers/acpi/apei/ghes.c @@ -749,7 +749,7 @@ static DEFINE_KFIFO(cxl_cper_prot_err_fi CXL_CPER_PROT_ERR_FIFO_DEPTH); /* Synchronize schedule_work() with cxl_cper_prot_err_work changes */ -static DEFINE_SPINLOCK(cxl_cper_prot_err_work_lock); +static DEFINE_RAW_SPINLOCK(cxl_cper_prot_err_work_lock); struct work_struct *cxl_cper_prot_err_work; static void cxl_cper_post_prot_err(struct cxl_cper_sec_prot_err *prot_err, @@ -761,7 +761,7 @@ static void cxl_cper_post_prot_err(struc if (cxl_cper_sec_prot_err_valid(prot_err)) return; - guard(spinlock_irqsave)(&cxl_cper_prot_err_work_lock); + guard(raw_spinlock_irqsave)(&cxl_cper_prot_err_work_lock); if (!cxl_cper_prot_err_work) return; @@ -780,10 +780,11 @@ static void cxl_cper_post_prot_err(struc int cxl_cper_register_prot_err_work(struct work_struct *work) { - if (cxl_cper_prot_err_work) - return -EINVAL; + guard(raw_spinlock_irqsave)(&cxl_cper_prot_err_work_lock); - guard(spinlock)(&cxl_cper_prot_err_work_lock); + if (WARN_ONCE(cxl_cper_prot_err_work, + "CPER-CXL kfifo consumer already registered\n")) + return -EINVAL; cxl_cper_prot_err_work = work; return 0; } @@ -791,11 +792,18 @@ EXPORT_SYMBOL_NS_GPL(cxl_cper_register_p int cxl_cper_unregister_prot_err_work(struct work_struct *work) { - if (cxl_cper_prot_err_work != work) - return -EINVAL; + scoped_guard(raw_spinlock_irqsave, &cxl_cper_prot_err_work_lock) { + if (WARN_ONCE(cxl_cper_prot_err_work != work, + "CPER-CXL kfifo consumer mismatch on unregister\n")) + return -EINVAL; + cxl_cper_prot_err_work = NULL; + } + + cancel_work_sync(work); + + /* Discard stale entries so they are not replayed on next module load */ + kfifo_reset(&cxl_cper_prot_err_fifo); - guard(spinlock)(&cxl_cper_prot_err_work_lock); - cxl_cper_prot_err_work = NULL; return 0; } EXPORT_SYMBOL_NS_GPL(cxl_cper_unregister_prot_err_work, "CXL"); @@ -811,7 +819,7 @@ EXPORT_SYMBOL_NS_GPL(cxl_cper_prot_err_k DEFINE_KFIFO(cxl_cper_fifo, struct cxl_cper_work_data, CXL_CPER_FIFO_DEPTH); /* Synchronize schedule_work() with cxl_cper_work changes */ -static DEFINE_SPINLOCK(cxl_cper_work_lock); +static DEFINE_RAW_SPINLOCK(cxl_cper_work_lock); struct work_struct *cxl_cper_work; static void cxl_cper_post_event(enum cxl_event_type event_type, @@ -831,7 +839,7 @@ static void cxl_cper_post_event(enum cxl return; } - guard(spinlock_irqsave)(&cxl_cper_work_lock); + guard(raw_spinlock_irqsave)(&cxl_cper_work_lock); if (!cxl_cper_work) return; @@ -849,10 +857,11 @@ static void cxl_cper_post_event(enum cxl int cxl_cper_register_work(struct work_struct *work) { - if (cxl_cper_work) + guard(raw_spinlock_irqsave)(&cxl_cper_work_lock); + if (WARN_ONCE(cxl_cper_work, + "CXL CPER kfifo consumer already registered\n")) return -EINVAL; - guard(spinlock)(&cxl_cper_work_lock); cxl_cper_work = work; return 0; } @@ -860,11 +869,18 @@ EXPORT_SYMBOL_NS_GPL(cxl_cper_register_w int cxl_cper_unregister_work(struct work_struct *work) { - if (cxl_cper_work != work) - return -EINVAL; + scoped_guard(raw_spinlock_irqsave, &cxl_cper_work_lock) { + if (WARN_ONCE(cxl_cper_work != work, + "CXL CPER kfifo consumer mismatch on unregister\n")) + return -EINVAL; + cxl_cper_work = NULL; + } + + cancel_work_sync(work); + + /* Discard stale entries so they are not replayed on next module load */ + kfifo_reset(&cxl_cper_fifo); - guard(spinlock)(&cxl_cper_work_lock); - cxl_cper_work = NULL; return 0; } EXPORT_SYMBOL_NS_GPL(cxl_cper_unregister_work, "CXL"); --- a/drivers/cxl/core/ras.c +++ b/drivers/cxl/core/ras.c @@ -137,7 +137,6 @@ int cxl_ras_init(void) void cxl_ras_exit(void) { cxl_cper_unregister_prot_err_work(&cxl_cper_prot_err_work); - cancel_work_sync(&cxl_cper_prot_err_work); } static void cxl_dport_map_ras(struct cxl_dport *dport) --- a/drivers/cxl/pci.c +++ b/drivers/cxl/pci.c @@ -1083,7 +1083,6 @@ static int __init cxl_pci_driver_init(vo static void __exit cxl_pci_driver_exit(void) { cxl_cper_unregister_work(&cxl_cper_work); - cancel_work_sync(&cxl_cper_work); pci_unregister_driver(&cxl_pci_driver); }