Hi,
I'm using linux-2.6.26 with Freescale patches and the
adeos-ipipe-2.6.26-powerpc-DENX-2.2-04.patch from xenomai-2.4.5 on a
Freescale PowerPC MPC8360.
I was calling 'vprintk' (kernel/printk.c) from within a Xenomai task
which lead to a Linux freeze.
After some investigation, I found out that just 'printk' is "Ipipe
aware" (printk is implemented differently if CONFIG_IPIPE is defined)
but not 'vprintk'.
I rearranged the code (see patch) which actually does the job and makes
'vprintk' "Ipipe aware", too. The original 'vprintk' funktion was
renamed '__vprintk'.
I tested the code. My kernel boots fine and I can call vprintk from
within a Xenomai task. Do you have any concerns with this approach?
Andreas
--- linux-source-2.6.26/kernel/printk.c 2008-12-10 18:06:03.000000000 -0500
+++ linux-source-2.6.26.mod/kernel/printk.c 2008-12-17 09:40:24.000000000 -0500
@@ -583,41 +583,6 @@
return 0;
}
-#ifdef CONFIG_IPIPE
-
-static ipipe_spinlock_t __ipipe_printk_lock = IPIPE_SPIN_LOCK_UNLOCKED;
-
-static int __ipipe_printk_fill;
-
-static char __ipipe_printk_buf[__LOG_BUF_LEN];
-
-void __ipipe_flush_printk (unsigned virq, void *cookie)
-{
- char *p = __ipipe_printk_buf;
- int len, lmax, out = 0;
- unsigned long flags;
-
- goto start;
-
- do {
- spin_unlock_irqrestore(&__ipipe_printk_lock, flags);
- start:
- lmax = __ipipe_printk_fill;
- while (out < lmax) {
- len = strlen(p) + 1;
- printk("%s",p);
- p += len;
- out += len;
- }
- spin_lock_irqsave(&__ipipe_printk_lock, flags);
- }
- while (__ipipe_printk_fill != lmax);
-
- __ipipe_printk_fill = 0;
-
- spin_unlock_irqrestore(&__ipipe_printk_lock, flags);
-}
-
/**
* printk - print a kernel message
* @fmt: format string
@@ -640,48 +605,6 @@
* See also:
* printf(3)
*/
-
-asmlinkage int printk(const char *fmt, ...)
-{
- int r, fbytes, oldcount, cs = -1;
- unsigned long flags;
- va_list args;
-
- va_start(args, fmt);
-
- if (test_bit(IPIPE_SPRINTK_FLAG,&ipipe_current_domain->flags) ||
- oops_in_progress)
- cs = ipipe_disable_context_check(ipipe_processor_id());
-
- if (ipipe_current_domain == ipipe_root_domain || cs != -1) {
- r = vprintk(fmt, args);
- if (cs != -1)
- ipipe_restore_context_check(ipipe_processor_id(), cs);
- goto out;
- }
-
- spin_lock_irqsave(&__ipipe_printk_lock, flags);
-
- oldcount = __ipipe_printk_fill;
- fbytes = __LOG_BUF_LEN - oldcount;
-
- if (fbytes > 1) {
- r = vscnprintf(__ipipe_printk_buf + __ipipe_printk_fill,
- fbytes, fmt, args) + 1; /* account for the null byte */
- __ipipe_printk_fill += r;
- } else
- r = 0;
-
- spin_unlock_irqrestore(&__ipipe_printk_lock, flags);
-
- if (oldcount == 0)
- ipipe_trigger_irq(__ipipe_printk_virq);
-out:
- va_end(args);
-
- return r;
-}
-#else /* !CONFIG_IPIPE */
asmlinkage int printk(const char *fmt, ...)
{
va_list args;
@@ -693,7 +616,6 @@
return r;
}
-#endif /* CONFIG_IPIPE */
/* cpu currently holding logbuf_lock */
static volatile unsigned int printk_cpu = UINT_MAX;
@@ -749,7 +671,11 @@
KERN_CRIT "BUG: recent printk recursion!\n";
static int printk_recursion_bug;
+#ifdef CONFIG_IPIPE
+asmlinkage int __vprintk(const char *fmt, va_list args)
+#else /* !CONFIG_IPIPE */
asmlinkage int vprintk(const char *fmt, va_list args)
+#endif /* !CONFIG_IPIPE */
{
static int log_level_unknown = 1;
static char printk_buf[1024];
@@ -874,6 +800,78 @@
preempt_enable();
return printed_len;
}
+
+#ifdef CONFIG_IPIPE
+static ipipe_spinlock_t __ipipe_printk_lock = IPIPE_SPIN_LOCK_UNLOCKED;
+
+static int __ipipe_printk_fill;
+
+static char __ipipe_printk_buf[__LOG_BUF_LEN];
+
+void __ipipe_flush_printk (unsigned virq, void *cookie)
+{
+ char *p = __ipipe_printk_buf;
+ int len, lmax, out = 0;
+ unsigned long flags;
+
+ goto start;
+
+ do {
+ spin_unlock_irqrestore(&__ipipe_printk_lock, flags);
+ start:
+ lmax = __ipipe_printk_fill;
+ while (out < lmax) {
+ len = strlen(p) + 1;
+ printk("%s",p);
+ p += len;
+ out += len;
+ }
+ spin_lock_irqsave(&__ipipe_printk_lock, flags);
+ }
+ while (__ipipe_printk_fill != lmax);
+
+ __ipipe_printk_fill = 0;
+
+ spin_unlock_irqrestore(&__ipipe_printk_lock, flags);
+}
+
+asmlinkage int vprintk(const char *fmt, va_list args)
+{
+ int r, fbytes, oldcount, cs = -1;
+ unsigned long flags;
+
+ if (test_bit(IPIPE_SPRINTK_FLAG,&ipipe_current_domain->flags) ||
+ oops_in_progress)
+ cs = ipipe_disable_context_check(ipipe_processor_id());
+
+ if (ipipe_current_domain == ipipe_root_domain || cs != -1) {
+ r = __vprintk(fmt, args);
+ if (cs != -1)
+ ipipe_restore_context_check(ipipe_processor_id(), cs);
+ goto out;
+ }
+
+ spin_lock_irqsave(&__ipipe_printk_lock, flags);
+
+ oldcount = __ipipe_printk_fill;
+ fbytes = __LOG_BUF_LEN - oldcount;
+
+ if (fbytes > 1) {
+ r = vscnprintf(__ipipe_printk_buf + __ipipe_printk_fill,
+ fbytes, fmt, args) + 1; /* account for the null byte */
+ __ipipe_printk_fill += r;
+ } else
+ r = 0;
+
+ spin_unlock_irqrestore(&__ipipe_printk_lock, flags);
+
+ if (oldcount == 0)
+ ipipe_trigger_irq(__ipipe_printk_virq);
+out:
+ return r;
+}
+#endif /* CONFIG_IPIPE */
+
EXPORT_SYMBOL(printk);
EXPORT_SYMBOL(vprintk);
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