linux-kernel - [PATCH v2 23/23] netoops: Add an interface to trigger various types of crashes.

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Message-ID: <20101108203352.22479.15302.stgit@crlf.mtv.corp.google.com>
Date:	Mon, 08 Nov 2010 12:33:53 -0800
From:	Mike Waychison <mikew@...gle.com>
To:	simon.kagstrom@...insight.net, davem@...emloft.net,
	nhorman@...driver.com, Matt Mackall <mpm@...enic.com>
Cc:	adurbin@...gle.com, linux-kernel@...r.kernel.org,
	chavey@...gle.com, Greg KH <greg@...ah.com>,
	Américo Wang <xiyou.wangcong@...il.com>,
	akpm@...ux-foundation.org, linux-api@...r.kernel.org
Subject: [PATCH v2 23/23] netoops: Add an interface to trigger various types
	of crashes.

It is very useful to be able to test the crash path, but in order to do so, we
need to expose various ways to crash the kernel in a deterministic fashion.

This commit adds a file, /proc/sys/kernel/net_dump_now that takes various
tokens that will crash the kernel in various ways.

This requires kmsg_dump() be accessible to modules, so export it.

Signed-off-by: Mike Waychison <mikew@...gle.com>
---
Changelog:
- v2
   - Folded EXPORT_SYMBOL_GPL(kmsg_dump) into this patch

TODO: User visible ABI needs a better interface
---
 drivers/net/netoops.c |   31 +++++++++++++++++++++++++++++++
 kernel/printk.c       |    1 +
 2 files changed, 32 insertions(+), 0 deletions(-)

diff --git a/drivers/net/netoops.c b/drivers/net/netoops.c
index 1ffd0f0..60683c5 100644
--- a/drivers/net/netoops.c
+++ b/drivers/net/netoops.c
@@ -288,6 +288,32 @@ static struct kmsg_dumper netoops_dumper = {
 	.dump = netoops,
 };
 
+static int proc_netoops_now(struct ctl_table *table, int write,
+			    void __user *buffer, size_t *lenp, loff_t *ppos)
+{
+	if (write) {
+		char magic[20];
+		/* just crash in kernel mode. */
+		if (copy_from_user(magic, buffer, min(*lenp, sizeof(magic))))
+			return -EFAULT;
+		magic[min(*lenp, sizeof(magic))-1] = 0;
+		if (!strcmp(magic, "elgooG")) {
+			/* Test a simple crash */
+			*(unsigned long *)0 = 0;
+		} else if (!strcmp(magic, "guB")) {
+			/* Test the BUG() handler */
+			BUG();
+		} else if (!strcmp(magic, "cinaP")) {
+			panic("Testing panic");
+		} else if (!strcmp(magic, "pmuD")) {
+			kmsg_dump(KMSG_DUMP_SOFT, NULL);
+		}
+		return 0;
+	}
+	*lenp = 0;
+	return 0;
+}
+
 static struct ctl_table kern_table[] = {
 	{
 		.procname       = "net_dump_one_shot",
@@ -296,6 +322,11 @@ static struct ctl_table kern_table[] = {
 		.mode           = 0644,
 		.proc_handler   = &proc_dointvec,
 	},
+	{
+		.procname       = "net_dump_now",
+		.mode           = 0600,
+		.proc_handler   = &proc_netoops_now,
+	},
 	{},
 };
 
diff --git a/kernel/printk.c b/kernel/printk.c
index 159b4d6..9323339 100644
--- a/kernel/printk.c
+++ b/kernel/printk.c
@@ -1573,4 +1573,5 @@ void kmsg_dump(enum kmsg_dump_reason reason, struct pt_regs *pt_regs)
 		dumper->dump(dumper, reason, pt_regs, s1, l1, s2, l2);
 	spin_unlock_irqrestore(&dump_list_lock, flags);
 }
+EXPORT_SYMBOL_GPL(kmsg_dump);
 #endif

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