From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.0 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE, SPF_PASS,T_DKIMWL_WL_HIGH,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2E2E5C2BCA1 for ; Sun, 9 Jun 2019 16:51:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id EF5EA206C3 for ; Sun, 9 Jun 2019 16:51:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1560099070; bh=LxIvHh/iYPn4Am1CEqmbscL4NNy5pXQ+zMra3YlbCvg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=ShGrNRZGv85T/Ey592YM/4wx6hHlNGRulTqahuumvcqVYWOOTCnPeCxi7YPlzhig6 5hvnkgGJjDJeaFIdQc3YyGlk9ULuS8D0C9LkTjNR0mywu2FKkfvQVLh9VTXhkj0d7O lihVjCfotSgYNO3CDAxcu+ZfCCSNXD04PfdYBZ5s= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731885AbfFIQvJ (ORCPT ); Sun, 9 Jun 2019 12:51:09 -0400 Received: from mail.kernel.org ([198.145.29.99]:51214 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731867AbfFIQvF (ORCPT ); Sun, 9 Jun 2019 12:51:05 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id E0F6A2083D; Sun, 9 Jun 2019 16:51:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1560099064; bh=LxIvHh/iYPn4Am1CEqmbscL4NNy5pXQ+zMra3YlbCvg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=HFxGPfWKBsv2tqhDqD9HQzCIZoPhLsZLoo+5p6T0q9L+m7txg8qFM3I0UM5b6XJWO 7SnRyjse6hRQgpgnGkJG/RnKzWvP4C/2i6n4HquKt7zNfvOf+Sy8qqs3gvyQ7zraoq O8UMZMGgtaVLRnRbuAtcUFRFSt+x9OxmhHWxoavw= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Sebastian Andrzej Siewior , Kees Cook Subject: [PATCH 4.14 17/35] pstore: Convert buf_lock to semaphore Date: Sun, 9 Jun 2019 18:42:23 +0200 Message-Id: <20190609164126.502935305@linuxfoundation.org> X-Mailer: git-send-email 2.21.0 In-Reply-To: <20190609164125.377368385@linuxfoundation.org> References: <20190609164125.377368385@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Kees Cook commit ea84b580b95521644429cc6748b6c2bf27c8b0f3 upstream. Instead of running with interrupts disabled, use a semaphore. This should make it easier for backends that may need to sleep (e.g. EFI) when performing a write: |BUG: sleeping function called from invalid context at kernel/sched/completion.c:99 |in_atomic(): 1, irqs_disabled(): 1, pid: 2236, name: sig-xstate-bum |Preemption disabled at: |[] pstore_dump+0x72/0x330 |CPU: 26 PID: 2236 Comm: sig-xstate-bum Tainted: G D 4.20.0-rc3 #45 |Call Trace: | dump_stack+0x4f/0x6a | ___might_sleep.cold.91+0xd3/0xe4 | __might_sleep+0x50/0x90 | wait_for_completion+0x32/0x130 | virt_efi_query_variable_info+0x14e/0x160 | efi_query_variable_store+0x51/0x1a0 | efivar_entry_set_safe+0xa3/0x1b0 | efi_pstore_write+0x109/0x140 | pstore_dump+0x11c/0x330 | kmsg_dump+0xa4/0xd0 | oops_exit+0x22/0x30 ... Reported-by: Sebastian Andrzej Siewior Fixes: 21b3ddd39fee ("efi: Don't use spinlocks for efi vars") Signed-off-by: Kees Cook Signed-off-by: Greg Kroah-Hartman --- arch/powerpc/kernel/nvram_64.c | 2 - drivers/acpi/apei/erst.c | 1 drivers/firmware/efi/efi-pstore.c | 4 --- fs/pstore/platform.c | 44 +++++++++++++++++++------------------- fs/pstore/ram.c | 1 include/linux/pstore.h | 7 ++---- 6 files changed, 27 insertions(+), 32 deletions(-) --- a/arch/powerpc/kernel/nvram_64.c +++ b/arch/powerpc/kernel/nvram_64.c @@ -566,8 +566,6 @@ static int nvram_pstore_init(void) nvram_pstore_info.buf = oops_data; nvram_pstore_info.bufsize = oops_data_sz; - spin_lock_init(&nvram_pstore_info.buf_lock); - rc = pstore_register(&nvram_pstore_info); if (rc && (rc != -EPERM)) /* Print error only when pstore.backend == nvram */ --- a/drivers/acpi/apei/erst.c +++ b/drivers/acpi/apei/erst.c @@ -1175,7 +1175,6 @@ static int __init erst_init(void) "Error Record Serialization Table (ERST) support is initialized.\n"); buf = kmalloc(erst_erange.size, GFP_KERNEL); - spin_lock_init(&erst_info.buf_lock); if (buf) { erst_info.buf = buf + sizeof(struct cper_pstore_record); erst_info.bufsize = erst_erange.size - --- a/drivers/firmware/efi/efi-pstore.c +++ b/drivers/firmware/efi/efi-pstore.c @@ -258,8 +258,7 @@ static int efi_pstore_write(struct pstor efi_name[i] = name[i]; ret = efivar_entry_set_safe(efi_name, vendor, PSTORE_EFI_ATTRIBUTES, - !pstore_cannot_block_path(record->reason), - record->size, record->psi->buf); + preemptible(), record->size, record->psi->buf); if (record->reason == KMSG_DUMP_OOPS) efivar_run_worker(); @@ -368,7 +367,6 @@ static __init int efivars_pstore_init(vo return -ENOMEM; efi_pstore_info.bufsize = 1024; - spin_lock_init(&efi_pstore_info.buf_lock); if (pstore_register(&efi_pstore_info)) { kfree(efi_pstore_info.buf); --- a/fs/pstore/platform.c +++ b/fs/pstore/platform.c @@ -129,26 +129,27 @@ static const char *get_reason_str(enum k } } -bool pstore_cannot_block_path(enum kmsg_dump_reason reason) +/* + * Should pstore_dump() wait for a concurrent pstore_dump()? If + * not, the current pstore_dump() will report a failure to dump + * and return. + */ +static bool pstore_cannot_wait(enum kmsg_dump_reason reason) { - /* - * In case of NMI path, pstore shouldn't be blocked - * regardless of reason. - */ + /* In NMI path, pstore shouldn't block regardless of reason. */ if (in_nmi()) return true; switch (reason) { /* In panic case, other cpus are stopped by smp_send_stop(). */ case KMSG_DUMP_PANIC: - /* Emergency restart shouldn't be blocked by spin lock. */ + /* Emergency restart shouldn't be blocked. */ case KMSG_DUMP_EMERG: return true; default: return false; } } -EXPORT_SYMBOL_GPL(pstore_cannot_block_path); #ifdef CONFIG_PSTORE_ZLIB_COMPRESS /* Derived from logfs_compress() */ @@ -499,23 +500,23 @@ static void pstore_dump(struct kmsg_dump unsigned long total = 0; const char *why; unsigned int part = 1; - unsigned long flags = 0; - int is_locked; int ret; why = get_reason_str(reason); - if (pstore_cannot_block_path(reason)) { - is_locked = spin_trylock_irqsave(&psinfo->buf_lock, flags); - if (!is_locked) { - pr_err("pstore dump routine blocked in %s path, may corrupt error record\n" - , in_nmi() ? "NMI" : why); + if (down_trylock(&psinfo->buf_lock)) { + /* Failed to acquire lock: give up if we cannot wait. */ + if (pstore_cannot_wait(reason)) { + pr_err("dump skipped in %s path: may corrupt error record\n", + in_nmi() ? "NMI" : why); + return; + } + if (down_interruptible(&psinfo->buf_lock)) { + pr_err("could not grab semaphore?!\n"); return; } - } else { - spin_lock_irqsave(&psinfo->buf_lock, flags); - is_locked = 1; } + oopscount++; while (total < kmsg_bytes) { char *dst; @@ -532,7 +533,7 @@ static void pstore_dump(struct kmsg_dump record.part = part; record.buf = psinfo->buf; - if (big_oops_buf && is_locked) { + if (big_oops_buf) { dst = big_oops_buf; dst_size = big_oops_buf_sz; } else { @@ -550,7 +551,7 @@ static void pstore_dump(struct kmsg_dump dst_size, &dump_size)) break; - if (big_oops_buf && is_locked) { + if (big_oops_buf) { zipped_len = pstore_compress(dst, psinfo->buf, header_size + dump_size, psinfo->bufsize); @@ -573,8 +574,8 @@ static void pstore_dump(struct kmsg_dump total += record.size; part++; } - if (is_locked) - spin_unlock_irqrestore(&psinfo->buf_lock, flags); + + up(&psinfo->buf_lock); } static struct kmsg_dumper pstore_dumper = { @@ -693,6 +694,7 @@ int pstore_register(struct pstore_info * psi->write_user = pstore_write_user_compat; psinfo = psi; mutex_init(&psinfo->read_mutex); + sema_init(&psinfo->buf_lock, 1); spin_unlock(&pstore_lock); if (owner && !try_module_get(owner)) { --- a/fs/pstore/ram.c +++ b/fs/pstore/ram.c @@ -812,7 +812,6 @@ static int ramoops_probe(struct platform err = -ENOMEM; goto fail_clear; } - spin_lock_init(&cxt->pstore.buf_lock); cxt->pstore.flags = PSTORE_FLAGS_DMESG; if (cxt->console_size) --- a/include/linux/pstore.h +++ b/include/linux/pstore.h @@ -26,7 +26,7 @@ #include #include #include -#include +#include #include #include @@ -88,7 +88,7 @@ struct pstore_record { * @owner: module which is repsonsible for this backend driver * @name: name of the backend driver * - * @buf_lock: spinlock to serialize access to @buf + * @buf_lock: semaphore to serialize access to @buf * @buf: preallocated crash dump buffer * @bufsize: size of @buf available for crash dump bytes (must match * smallest number of bytes available for writing to a @@ -173,7 +173,7 @@ struct pstore_info { struct module *owner; char *name; - spinlock_t buf_lock; + struct semaphore buf_lock; char *buf; size_t bufsize; @@ -199,7 +199,6 @@ struct pstore_info { extern int pstore_register(struct pstore_info *); extern void pstore_unregister(struct pstore_info *); -extern bool pstore_cannot_block_path(enum kmsg_dump_reason reason); struct pstore_ftrace_record { unsigned long ip;