linux-kernel - [RFC PATCH v6 07/10] fadump: Introduce cleanup routine to invalidate /proc/vmcore.

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Message-ID: <20111210065103.10195.1172.stgit@mars.in.ibm.com>
Date:	Sat, 10 Dec 2011 12:21:03 +0530
From:	Mahesh J Salgaonkar <mahesh@...ux.vnet.ibm.com>
To:	linuxppc-dev <linuxppc-dev@...abs.org>,
	Linux Kernel <linux-kernel@...r.kernel.org>,
	Benjamin Herrenschmidt <benh@...nel.crashing.org>
Cc:	Amerigo Wang <amwang@...hat.com>,
	Kexec-ml <kexec@...ts.infradead.org>,
	Milton Miller <miltonm@....com>,
	Haren Myneni <hbabu@...ibm.com>,
	Randy Dunlap <rdunlap@...otime.net>,
	"Eric W. Biederman" <ebiederm@...ssion.com>,
	Ananth Narayan <ananth@...ibm.com>,
	Vivek Goyal <vgoyal@...hat.com>,
	Anton Blanchard <anton@...ba.org>
Subject: [RFC PATCH v6 07/10] fadump: Introduce cleanup routine to invalidate
	/proc/vmcore.

From: Mahesh Salgaonkar <mahesh@...ux.vnet.ibm.com>

With the firmware-assisted dump support we don't require a reboot when we
are in second kernel after crash. The second kernel after crash is a normal
kernel boot and has knowledge about entire system RAM with the page tables
initialized for entire system RAM. Hence once the dump is saved to disk, we
can just release the reserved memory area for general use and continue
with second kernel as production kernel.

Hence when we release the reserved memory that contains dump data, the
'/proc/vmcore' will not be valid anymore. Hence this patch introduces
a cleanup routine that invalidates and removes the /proc/vmcore file. This
routine will be invoked before we release the reserved dump memory area.

Signed-off-by: Mahesh Salgaonkar <mahesh@...ux.vnet.ibm.com>
---
 fs/proc/vmcore.c |   23 +++++++++++++++++++++++
 1 files changed, 23 insertions(+), 0 deletions(-)

diff --git a/fs/proc/vmcore.c b/fs/proc/vmcore.c
index b0f450a..0d5071d 100644
--- a/fs/proc/vmcore.c
+++ b/fs/proc/vmcore.c
@@ -700,3 +700,26 @@ static int __init vmcore_init(void)
 	return 0;
 }
 module_init(vmcore_init)
+
+/* Cleanup function for vmcore module. */
+void vmcore_cleanup(void)
+{
+	struct list_head *pos, *next;
+
+	if (proc_vmcore) {
+		remove_proc_entry(proc_vmcore->name, proc_vmcore->parent);
+		proc_vmcore = NULL;
+	}
+
+	/* clear the vmcore list. */
+	list_for_each_safe(pos, next, &vmcore_list) {
+		struct vmcore *m;
+
+		m = list_entry(pos, struct vmcore, list);
+		list_del(&m->list);
+		kfree(m);
+	}
+	kfree(elfcorebuf);
+	elfcorebuf = NULL;
+}
+EXPORT_SYMBOL_GPL(vmcore_cleanup);

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