[PATCH 12/13] RFC ONLY - kgdb,kdb: use async breakpoint for sysrq for usb

[Jason Wessel <jason.wessel@xxxxxxxxxxxxx>]

This is a RFC patch.  The work to possibly merge kdb and kgdb is being
evaluated and this patch is considered only a proof of concept or
prototype.

For kdb, the usb keyboard will become disabled if you use a sysrq
sequence to enter kdb.  Using a tasklet solves the problem.

Signed-off-by: Jason Wessel <jason.wessel@xxxxxxxxxxxxx>
---
 kernel/kgdb.c |   12 +++++++++++-
 1 files changed, 11 insertions(+), 1 deletions(-)

diff --git a/kernel/kgdb.c b/kernel/kgdb.c
index f303410..034f6eb 100644
--- a/kernel/kgdb.c
+++ b/kernel/kgdb.c
@@ -1817,8 +1817,18 @@ static void sysrq_handle_gdb(int key, struct tty_struct 
*tty)
                printk(KERN_CRIT "Entering KGDB\n");
 #endif
        }
-
+#ifdef CONFIG_KDB_USB
+       /* XXX FIX ME XXX
+        * For now force the sysrq break point to be in a tasklet
+        * else if you send it from a usb keyboard, the keyboard cannot be
+        * used to interact with kdb because all the locks for the USB hcd
+        * device will be held.  This probably needs a run time check
+        * against what i/o driver submitted the breakpoint request.
+        */
+       kgdb_schedule_breakpoint();
+#else /* ! CONFIG_KDB_USB */
        kgdb_breakpoint();
+#endif /* CONFIG_KDB_USB */
 }
 
 static struct sysrq_key_op sysrq_gdb_op = {
-- 
1.6.3.rc0.1.gf800