aboutsummaryrefslogtreecommitdiffstats
path: root/drivers/char
diff options
context:
space:
mode:
authorJeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>2009-10-20 02:28:21 -0400
committerJeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>2009-11-03 14:05:51 -0500
commit7825cf10e31c64ece3cac66fb01a742f1094da51 (patch)
tree45de3111641487d1deb18cfb86200113e2427b0b /drivers/char
parent973df35ed9ff7806403e793a2ad7e9bd4c2fd2a9 (diff)
xen/hvc: make sure console output is always emitted, with explicit polling
We never want to rely on the hvc workqueue to emit output, because the most interesting output is when the kernel is broken. This will improve oops/crash/console message for better debugging. Instead, we force-poll until all output is emitted. Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> Cc: Stable Kernel <stable@kernel.org>
Diffstat (limited to 'drivers/char')
-rw-r--r--drivers/char/hvc_xen.c25
1 files changed, 24 insertions, 1 deletions
diff --git a/drivers/char/hvc_xen.c b/drivers/char/hvc_xen.c
index eba999f8598d..a6ee32b599a8 100644
--- a/drivers/char/hvc_xen.c
+++ b/drivers/char/hvc_xen.c
@@ -55,7 +55,7 @@ static inline void notify_daemon(void)
55 notify_remote_via_evtchn(xen_start_info->console.domU.evtchn); 55 notify_remote_via_evtchn(xen_start_info->console.domU.evtchn);
56} 56}
57 57
58static int write_console(uint32_t vtermno, const char *data, int len) 58static int __write_console(const char *data, int len)
59{ 59{
60 struct xencons_interface *intf = xencons_interface(); 60 struct xencons_interface *intf = xencons_interface();
61 XENCONS_RING_IDX cons, prod; 61 XENCONS_RING_IDX cons, prod;
@@ -76,6 +76,29 @@ static int write_console(uint32_t vtermno, const char *data, int len)
76 return sent; 76 return sent;
77} 77}
78 78
79static int write_console(uint32_t vtermno, const char *data, int len)
80{
81 int ret = len;
82
83 /*
84 * Make sure the whole buffer is emitted, polling if
85 * necessary. We don't ever want to rely on the hvc daemon
86 * because the most interesting console output is when the
87 * kernel is crippled.
88 */
89 while (len) {
90 int sent = __write_console(data, len);
91
92 data += sent;
93 len -= sent;
94
95 if (unlikely(len))
96 HYPERVISOR_sched_op(SCHEDOP_yield, NULL);
97 }
98
99 return ret;
100}
101
79static int read_console(uint32_t vtermno, char *buf, int len) 102static int read_console(uint32_t vtermno, char *buf, int len)
80{ 103{
81 struct xencons_interface *intf = xencons_interface(); 104 struct xencons_interface *intf = xencons_interface();