linux-kernel - [PATCH 02/18] pstore: Shut down worker when unregistering

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Message-Id: <1488837332-71582-3-git-send-email-keescook@chromium.org>
Date:   Mon,  6 Mar 2017 13:55:16 -0800
From:   Kees Cook <keescook@...omium.org>
To:     linux-kernel@...r.kernel.org
Cc:     Kees Cook <keescook@...omium.org>, stable@...r.kernel.org,
        Nobuhiro Iwamatsu <nobuhiro.iwamatsu.kw@...achi.com>,
        Qiuxu Zhuo <qiuxu.zhuo@...el.com>,
        Ard Biesheuvel <ard.biesheuvel@...aro.org>,
        Anton Vorontsov <anton@...msg.org>,
        Colin Cross <ccross@...roid.com>,
        Tony Luck <tony.luck@...el.com>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Michael Ellerman <mpe@...erman.id.au>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Len Brown <lenb@...nel.org>,
        Matt Fleming <matt@...eblueprint.co.uk>,
        Nathan Fontenot <nfont@...ux.vnet.ibm.com>,
        Pan Xinhui <xinhui.pan@...ux.vnet.ibm.com>,
        Daniel Axtens <dja@...ens.net>,
        Paul Gortmaker <paul.gortmaker@...driver.com>,
        Geliang Tang <geliangtang@....com>,
        linuxppc-dev@...ts.ozlabs.org, linux-acpi@...r.kernel.org,
        linux-efi@...r.kernel.org, linux-doc@...r.kernel.org
Subject: [PATCH 02/18] pstore: Shut down worker when unregistering

When built as a module and running with update_ms >= 0, pstore will Oops
during module unload since the work timer is still running. This makes sure
the worker is stopped before unloading.

Signed-off-by: Kees Cook <keescook@...omium.org>
Cc: stable@...r.kernel.org
---
 fs/pstore/platform.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/fs/pstore/platform.c b/fs/pstore/platform.c
index cfc1abd264d9..074fe85a2078 100644
--- a/fs/pstore/platform.c
+++ b/fs/pstore/platform.c
@@ -709,6 +709,7 @@ int pstore_register(struct pstore_info *psi)
 	if (psi->flags & PSTORE_FLAGS_PMSG)
 		pstore_register_pmsg();
 
+	/* Start watching for new records, if desired. */
 	if (pstore_update_ms >= 0) {
 		pstore_timer.expires = jiffies +
 			msecs_to_jiffies(pstore_update_ms);
@@ -731,6 +732,11 @@ EXPORT_SYMBOL_GPL(pstore_register);
 
 void pstore_unregister(struct pstore_info *psi)
 {
+	/* Stop timer and make sure all work has finished. */
+	pstore_update_ms = -1;
+	del_timer_sync(&pstore_timer);
+	flush_work(&pstore_work);
+
 	if (psi->flags & PSTORE_FLAGS_PMSG)
 		pstore_unregister_pmsg();
 	if (psi->flags & PSTORE_FLAGS_FTRACE)
@@ -830,7 +836,9 @@ static void pstore_timefunc(unsigned long dummy)
 		schedule_work(&pstore_work);
 	}
 
-	mod_timer(&pstore_timer, jiffies + msecs_to_jiffies(pstore_update_ms));
+	if (pstore_update_ms >= 0)
+		mod_timer(&pstore_timer,
+			  jiffies + msecs_to_jiffies(pstore_update_ms));
 }
 
 module_param(backend, charp, 0444);
-- 
2.7.4