Merge git://git.infradead.org/mtd-2.6

[pandora-kernel.git] / kernel / printk.c

diff --git a/kernel/printk.c b/kernel/printk.c
index b5ac4d9..1ded8e7 100644 (file)
--- a/kernel/printk.c
+++ b/kernel/printk.c
@@ -34,6 +34,7 @@
 #include <linux/syscalls.h>
 #include <linux/kexec.h>
 #include <linux/ratelimit.h>
+#include <linux/kmsg_dump.h>
 
 #include <asm/uaccess.h>
 
@@ -1405,4 +1406,122 @@ bool printk_timed_ratelimit(unsigned long *caller_jiffies,
        return false;
 }
 EXPORT_SYMBOL(printk_timed_ratelimit);
+
+static DEFINE_SPINLOCK(dump_list_lock);
+static LIST_HEAD(dump_list);
+
+/**
+ * kmsg_dump_register - register a kernel log dumper.
+ * @dump: pointer to the kmsg_dumper structure
+ *
+ * Adds a kernel log dumper to the system. The dump callback in the
+ * structure will be called when the kernel oopses or panics and must be
+ * set. Returns zero on success and %-EINVAL or %-EBUSY otherwise.
+ */
+int kmsg_dump_register(struct kmsg_dumper *dumper)
+{
+       unsigned long flags;
+       int err = -EBUSY;
+
+       /* The dump callback needs to be set */
+       if (!dumper->dump)
+               return -EINVAL;
+
+       spin_lock_irqsave(&dump_list_lock, flags);
+       /* Don't allow registering multiple times */
+       if (!dumper->registered) {
+               dumper->registered = 1;
+               list_add_tail(&dumper->list, &dump_list);
+               err = 0;
+       }
+       spin_unlock_irqrestore(&dump_list_lock, flags);
+
+       return err;
+}
+EXPORT_SYMBOL_GPL(kmsg_dump_register);
+
+/**
+ * kmsg_dump_unregister - unregister a kmsg dumper.
+ * @dump: pointer to the kmsg_dumper structure
+ *
+ * Removes a dump device from the system. Returns zero on success and
+ * %-EINVAL otherwise.
+ */
+int kmsg_dump_unregister(struct kmsg_dumper *dumper)
+{
+       unsigned long flags;
+       int err = -EINVAL;
+
+       spin_lock_irqsave(&dump_list_lock, flags);
+       if (dumper->registered) {
+               dumper->registered = 0;
+               list_del(&dumper->list);
+               err = 0;
+       }
+       spin_unlock_irqrestore(&dump_list_lock, flags);
+
+       return err;
+}
+EXPORT_SYMBOL_GPL(kmsg_dump_unregister);
+
+static const char const *kmsg_reasons[] = {
+       [KMSG_DUMP_OOPS]        = "oops",
+       [KMSG_DUMP_PANIC]       = "panic",
+};
+
+static const char *kmsg_to_str(enum kmsg_dump_reason reason)
+{
+       if (reason >= ARRAY_SIZE(kmsg_reasons) || reason < 0)
+               return "unknown";
+
+       return kmsg_reasons[reason];
+}
+
+/**
+ * kmsg_dump - dump kernel log to kernel message dumpers.
+ * @reason: the reason (oops, panic etc) for dumping
+ *
+ * Iterate through each of the dump devices and call the oops/panic
+ * callbacks with the log buffer.
+ */
+void kmsg_dump(enum kmsg_dump_reason reason)
+{
+       unsigned long end;
+       unsigned chars;
+       struct kmsg_dumper *dumper;
+       const char *s1, *s2;
+       unsigned long l1, l2;
+       unsigned long flags;
+
+       /* Theoretically, the log could move on after we do this, but
+          there's not a lot we can do about that. The new messages
+          will overwrite the start of what we dump. */
+       spin_lock_irqsave(&logbuf_lock, flags);
+       end = log_end & LOG_BUF_MASK;
+       chars = logged_chars;
+       spin_unlock_irqrestore(&logbuf_lock, flags);
+
+       if (logged_chars > end) {
+               s1 = log_buf + log_buf_len - logged_chars + end;
+               l1 = logged_chars - end;
+
+               s2 = log_buf;
+               l2 = end;
+       } else {
+               s1 = "";
+               l1 = 0;
+
+               s2 = log_buf + end - logged_chars;
+               l2 = logged_chars;
+       }
+
+       if (!spin_trylock_irqsave(&dump_list_lock, flags)) {
+               printk(KERN_ERR "dump_kmsg: dump list lock is held during %s, skipping dump\n",
+                               kmsg_to_str(reason));
+               return;
+       }
+       list_for_each_entry(dumper, &dump_list, list)
+               dumper->dump(dumper, reason, s1, l1, s2, l2);
+       spin_unlock_irqrestore(&dump_list_lock, flags);
+}
 #endif