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authorDaniel Thompson <daniel.thompson@linaro.org>2014-04-28 16:39:40 +0100
committerDaniel Thompson <daniel.thompson@linaro.org>2014-08-18 10:44:55 +0100
commit3497a5d8147ea0c71396a8dae16f9b425dfda84d (patch)
tree625cf6b7bfd22bac68db0b5ccee9a5bf814fbb4d
parentfedcc78db61520b947367e73381fff1f31c04809 (diff)
downloadlinux-3497a5d8147ea0c71396a8dae16f9b425dfda84d.tar.gz
kdb: Add framework to display sequence files
Lots of useful information about the system is held in pseudo filesystems and presented using the seq_file mechanism. Unfortunately during both boot up and kernel panic (both good times to break out kdb) it is difficult to examine these files. This patch introduces a means to display sequence files via kdb. Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org>
-rw-r--r--include/linux/kdb.h5
-rw-r--r--kernel/debug/kdb/kdb_io.c51
2 files changed, 56 insertions, 0 deletions
diff --git a/include/linux/kdb.h b/include/linux/kdb.h
index 290db1269c4c..fb46dd4299fe 100644
--- a/include/linux/kdb.h
+++ b/include/linux/kdb.h
@@ -25,6 +25,7 @@ typedef int (*kdb_func_t)(int, const char **);
#include <linux/init.h>
#include <linux/sched.h>
#include <linux/atomic.h>
+#include <linux/seq_file.h>
#define KDB_POLL_FUNC_MAX 5
extern int kdb_poll_idx;
@@ -117,6 +118,8 @@ extern __printf(1, 0) int vkdb_printf(const char *fmt, va_list args);
extern __printf(1, 2) int kdb_printf(const char *, ...);
typedef __printf(1, 2) int (*kdb_printf_t)(const char *, ...);
+extern int kdb_print_seq_file(const struct seq_operations *ops);
+
extern void kdb_init(int level);
/* Access to kdb specific polling devices */
@@ -151,6 +154,8 @@ extern int kdb_register_repeat(char *, kdb_func_t, char *, char *,
extern int kdb_unregister(char *);
#else /* ! CONFIG_KGDB_KDB */
static inline __printf(1, 2) int kdb_printf(const char *fmt, ...) { return 0; }
+static inline int
+kdb_print_seq_file(const struct seq_operations *ops) { return 0; }
static inline void kdb_init(int level) {}
static inline int kdb_register(char *cmd, kdb_func_t func, char *usage,
char *help, short minlen) { return 0; }
diff --git a/kernel/debug/kdb/kdb_io.c b/kernel/debug/kdb/kdb_io.c
index 7c70812caea5..e8444b23c37d 100644
--- a/kernel/debug/kdb/kdb_io.c
+++ b/kernel/debug/kdb/kdb_io.c
@@ -850,3 +850,54 @@ int kdb_printf(const char *fmt, ...)
return r;
}
EXPORT_SYMBOL_GPL(kdb_printf);
+
+/*
+ * Display a seq_file on the kdb console.
+ */
+
+static int __kdb_print_seq_file(struct seq_file *m, void *v)
+{
+ int i, res;
+
+ res = m->op->show(m, v);
+ if (0 != res)
+ return KDB_BADLENGTH;
+
+ for (i = 0; i < m->count && !KDB_FLAG(CMD_INTERRUPT); i++)
+ kdb_printf("%c", m->buf[i]);
+ m->count = 0;
+
+ return 0;
+}
+
+int kdb_print_seq_file(const struct seq_operations *ops)
+{
+ static char seq_buf[4096];
+ static DEFINE_SPINLOCK(seq_buf_lock);
+ unsigned long flags;
+ struct seq_file m = {
+ .buf = seq_buf,
+ .size = sizeof(seq_buf),
+ /* .lock is deliberately uninitialized to help reveal
+ * unsupportable show methods
+ */
+ .op = ops,
+ };
+ loff_t pos = 0;
+ void *v;
+ int res = 0;
+
+ v = ops->start(&m, &pos);
+ while (v) {
+ spin_lock_irqsave(&seq_buf_lock, flags);
+ res = __kdb_print_seq_file(&m, v);
+ spin_unlock_irqrestore(&seq_buf_lock, flags);
+ if (res != 0 || KDB_FLAG(CMD_INTERRUPT))
+ break;
+
+ v = ops->next(&m, v, &pos);
+ }
+ ops->stop(&m, v);
+
+ return res;
+}