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path: root/kernel/debug/kdb/kdb_io.c
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Diffstat (limited to 'kernel/debug/kdb/kdb_io.c')
-rw-r--r--kernel/debug/kdb/kdb_io.c37
1 files changed, 13 insertions, 24 deletions
diff --git a/kernel/debug/kdb/kdb_io.c b/kernel/debug/kdb/kdb_io.c
index 98c9011eac78..e74be38245ad 100644
--- a/kernel/debug/kdb/kdb_io.c
+++ b/kernel/debug/kdb/kdb_io.c
@@ -30,6 +30,7 @@
char kdb_prompt_str[CMD_BUFLEN];
int kdb_trap_printk;
+int kdb_printf_cpu = -1;
static int kgdb_transition_check(char *buffer)
{
@@ -554,31 +555,26 @@ int vkdb_printf(enum kdb_msgsrc src, const char *fmt, va_list ap)
int linecount;
int colcount;
int logging, saved_loglevel = 0;
- int saved_trap_printk;
- int got_printf_lock = 0;
int retlen = 0;
int fnd, len;
+ int this_cpu, old_cpu;
char *cp, *cp2, *cphold = NULL, replaced_byte = ' ';
char *moreprompt = "more> ";
struct console *c = console_drivers;
- static DEFINE_SPINLOCK(kdb_printf_lock);
unsigned long uninitialized_var(flags);
- preempt_disable();
- saved_trap_printk = kdb_trap_printk;
- kdb_trap_printk = 0;
-
/* Serialize kdb_printf if multiple cpus try to write at once.
* But if any cpu goes recursive in kdb, just print the output,
* even if it is interleaved with any other text.
*/
- if (!KDB_STATE(PRINTF_LOCK)) {
- KDB_STATE_SET(PRINTF_LOCK);
- spin_lock_irqsave(&kdb_printf_lock, flags);
- got_printf_lock = 1;
- atomic_inc(&kdb_event);
- } else {
- __acquire(kdb_printf_lock);
+ local_irq_save(flags);
+ this_cpu = smp_processor_id();
+ for (;;) {
+ old_cpu = cmpxchg(&kdb_printf_cpu, -1, this_cpu);
+ if (old_cpu == -1 || old_cpu == this_cpu)
+ break;
+
+ cpu_relax();
}
diag = kdbgetintenv("LINES", &linecount);
@@ -847,16 +843,9 @@ kdb_print_out:
suspend_grep = 0; /* end of what may have been a recursive call */
if (logging)
console_loglevel = saved_loglevel;
- if (KDB_STATE(PRINTF_LOCK) && got_printf_lock) {
- got_printf_lock = 0;
- spin_unlock_irqrestore(&kdb_printf_lock, flags);
- KDB_STATE_CLEAR(PRINTF_LOCK);
- atomic_dec(&kdb_event);
- } else {
- __release(kdb_printf_lock);
- }
- kdb_trap_printk = saved_trap_printk;
- preempt_enable();
+ /* kdb_printf_cpu locked the code above. */
+ smp_store_release(&kdb_printf_cpu, old_cpu);
+ local_irq_restore(flags);
return retlen;
}