diff options
| author | Frank Rowand <frank.rowand@am.sony.com> | 2011-09-23 13:43:12 -0700 |
|---|---|---|
| committer | Clark Williams <williams@redhat.com> | 2012-03-24 09:29:27 -0500 |
| commit | f828810e61c26fcb97dc9672dc44d47746577c3e (patch) | |
| tree | ac016665fb0bf5a7e450c00fd06c819ddc1c3bfc /drivers | |
| parent | 842480abd0a415a40389273e8cef3d5c1fa41645 (diff) | |
sysrq: Allow immediate Magic SysRq output for PREEMPT_RT_FULL
Add a CONFIG option to allow the output from Magic SysRq to be output
immediately, even if this causes large latencies.
If PREEMPT_RT_FULL, printk() will not try to acquire the console lock
when interrupts or preemption are disabled. If the console lock is
not acquired the printk() output will be buffered, but will not be
output immediately. Some drivers call into the Magic SysRq code
with interrupts or preemption disabled, so the output of Magic SysRq
will be buffered instead of printing immediately if this option is
not selected.
Even with this option selected, Magic SysRq output will be delayed
if the attempt to acquire the console lock fails.
Signed-off-by: Frank Rowand <frank.rowand@am.sony.com>
Link: http://lkml.kernel.org/r/4E7CEF60.5020508@am.sony.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/tty/serial/cpm_uart/cpm_uart_core.c | 2 | ||||
| -rw-r--r-- | drivers/tty/sysrq.c | 23 |
2 files changed, 24 insertions, 1 deletions
diff --git a/drivers/tty/serial/cpm_uart/cpm_uart_core.c b/drivers/tty/serial/cpm_uart/cpm_uart_core.c index b418947b7107..a8b05594e468 100644 --- a/drivers/tty/serial/cpm_uart/cpm_uart_core.c +++ b/drivers/tty/serial/cpm_uart/cpm_uart_core.c @@ -1226,7 +1226,7 @@ static void cpm_uart_console_write(struct console *co, const char *s, { struct uart_cpm_port *pinfo = &cpm_uart_ports[co->index]; unsigned long flags; - int nolock = oops_in_progress; + int nolock = oops_in_progress || sysrq_in_progress; if (unlikely(nolock)) { local_irq_save(flags); diff --git a/drivers/tty/sysrq.c b/drivers/tty/sysrq.c index 43db715f1502..5219738ffd11 100644 --- a/drivers/tty/sysrq.c +++ b/drivers/tty/sysrq.c @@ -492,6 +492,23 @@ static void __sysrq_put_key_op(int key, struct sysrq_key_op *op_p) sysrq_key_table[i] = op_p; } +#ifdef CONFIG_MAGIC_SYSRQ_FORCE_PRINTK + +int sysrq_in_progress; + +static void set_sysrq_in_progress(int value) +{ + sysrq_in_progress = value; +} + +#else + +static void set_sysrq_in_progress(int value) +{ +} + +#endif + void __handle_sysrq(int key, bool check_mask) { struct sysrq_key_op *op_p; @@ -500,6 +517,9 @@ void __handle_sysrq(int key, bool check_mask) unsigned long flags; spin_lock_irqsave(&sysrq_key_table_lock, flags); + + set_sysrq_in_progress(1); + /* * Raise the apparent loglevel to maximum so that the sysrq header * is shown to provide the user with positive feedback. We do not @@ -541,6 +561,9 @@ void __handle_sysrq(int key, bool check_mask) printk("\n"); console_loglevel = orig_log_level; } + + set_sysrq_in_progress(0); + spin_unlock_irqrestore(&sysrq_key_table_lock, flags); } |