linux-kernel - [PATCH v3 2/9] pstore: add debugfs support for causing dumps and panics

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Date:	Thu, 18 Oct 2012 14:06:00 +0300
From:	dragos.tatulea@...el.com
To:	ccross@...roid.com, keescook@...omium.org, tony.luck@...el.com,
	cbouatmailru@...il.com, linux-kernel@...r.kernel.org
Cc:	adrian.hunter@...el.com, octavian.purdila@...el.com
Subject: [PATCH v3 2/9] pstore: add debugfs support for causing dumps and panics

From: Adrian Hunter <adrian.hunter@...el.com>

There are 2 debugfs files:

	pstore/dump	writing a kmsg dump reason code
			will cause a dump to persistent
			storage

	pstore/panic	writing anything will cause
			a panic

Signed-off-by: Adrian Hunter <adrian.hunter@...el.com>
---
 fs/pstore/platform.c |   51 ++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 51 insertions(+)

diff --git a/fs/pstore/platform.c b/fs/pstore/platform.c
index c4ea778..9d65723 100644
--- a/fs/pstore/platform.c
+++ b/fs/pstore/platform.c
@@ -33,6 +33,7 @@
 #include <linux/hardirq.h>
 #include <linux/jiffies.h>
 #include <linux/workqueue.h>
+#include <linux/debugfs.h>
 
 #include "internal.h"
 
@@ -206,6 +207,54 @@ static int pstore_write_compat(enum pstore_type_id type,
 	return psi->write_buf(type, reason, id, part, psinfo->buf, size, psi);
 }
 
+#ifdef CONFIG_DEBUG_FS
+
+static DEFINE_SPINLOCK(dbg_lock);
+
+static int dbg_dump(void *data, u64 val)
+{
+	unsigned long flags;
+
+	switch (val) {
+	case KMSG_DUMP_PANIC:
+	case KMSG_DUMP_OOPS:
+	case KMSG_DUMP_EMERG:
+	case KMSG_DUMP_RESTART:
+	case KMSG_DUMP_HALT:
+	case KMSG_DUMP_POWEROFF:
+		spin_lock_irqsave(&dbg_lock, flags);
+		kmsg_dump(val);
+		spin_unlock_irqrestore(&dbg_lock, flags);
+		return 0;
+	}
+	return -EINVAL;
+}
+DEFINE_SIMPLE_ATTRIBUTE(dbg_dump_fops, NULL, dbg_dump, "%llu\n");
+
+static int dbg_panic(void *data, u64 val)
+{
+	panic(KERN_EMERG "pstore debugging panic!\n");
+	return 0;
+}
+DEFINE_SIMPLE_ATTRIBUTE(dbg_panic_fops, NULL, dbg_panic, "%llu\n");
+
+static void pstore_debugfs_init(void)
+{
+	struct dentry *root;
+
+	root = debugfs_create_dir("pstore", NULL);
+	debugfs_create_file("dump", S_IWUSR, root, NULL, &dbg_dump_fops);
+	debugfs_create_file("panic", S_IWUSR, root, NULL, &dbg_panic_fops);
+}
+
+#else
+
+static inline void pstore_debugfs_init(void)
+{
+}
+
+#endif
+
 /*
  * platform specific persistent storage driver registers with
  * us here. If pstore is already mounted, call the platform
@@ -257,6 +306,8 @@ int pstore_register(struct pstore_info *psi)
 		add_timer(&pstore_timer);
 	}
 
+	pstore_debugfs_init();
+
 	return 0;
 }
 EXPORT_SYMBOL_GPL(pstore_register);
-- 
1.7.9.5

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