Request for backport of [PARISC] pdc_console: fix bizarre panic on boot

[James Bottomley <James.Bottomley@HansenPartnership.com>]

Lack of this causes boot panics with the stable kernel on all 2.6.24.x
kernels.  The fix is upstream as:

commit ef1afd4d79f0479960ff36bb5fe6ec6eba1ebff2
Author: Kyle McMartin <kyle@shortfin.cabal.ca>
Date:   Mon Feb 18 23:34:34 2008 -0800

    [PARISC] pdc_console: fix bizarre panic on boot

James

---

From: Kyle McMartin <kyle@shortfin.cabal.ca>
Subject: [PARISC] pdc_console: fix bizarre panic on boot

Commit:

commit 721fdf34167580ff98263c74cead8871d76936e6
Author: Kyle McMartin <kyle@shortfin.cabal.ca>
Date:   Thu Dec 6 09:32:15 2007 -0800

    [PARISC] print more than one character at a time for pdc console

introduced a subtle bug by accidentally removing the "static" from
iodc_dbuf. This resulted in, what appeared to be, a trap without
*current set to a task. Probably the result of a trap in real mode
while calling firmware.

Also do other misc clean ups. Since the only input from firmware is non
blocking, share iodc_dbuf between input and output, and spinlock the
only callers.

[jejb: fixed up rejections against the stable tree]

Signed-off-by: Kyle McMartin <kyle@parisc-linux.org>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>

---
 arch/parisc/kernel/firmware.c |   27 +++++++++++++++++----------
 arch/parisc/kernel/pdc_cons.c |   19 +++++++++++++++++--
 include/asm-parisc/pdc.h      |    3 +--
 3 files changed, 35 insertions(+), 14 deletions(-)

diff --git a/arch/parisc/kernel/firmware.c b/arch/parisc/kernel/firmware.c
index 4ab83d5..7177a6c 100644
--- a/arch/parisc/kernel/firmware.c
+++ b/arch/parisc/kernel/firmware.c
@@ -1080,6 +1080,9 @@ void pdc_io_reset_devices(void)
 	spin_unlock_irqrestore(&pdc_lock, flags);
 }
 
+/* locked by pdc_console_lock */
+static int __attribute__((aligned(8)))   iodc_retbuf[32];
+static char __attribute__((aligned(64))) iodc_dbuf[4096];
 
 /**
  * pdc_iodc_print - Console print using IODC.
@@ -1091,24 +1094,20 @@ void pdc_io_reset_devices(void)
  * Since the HP console requires CR+LF to perform a 'newline', we translate
  * "\n" to "\r\n".
  */
-int pdc_iodc_print(unsigned char *str, unsigned count)
+int pdc_iodc_print(const unsigned char *str, unsigned count)
 {
-	/* XXX Should we spinlock posx usage */
 	static int posx;        /* for simple TAB-Simulation... */
-	int __attribute__((aligned(8)))   iodc_retbuf[32];
-	char __attribute__((aligned(64))) iodc_dbuf[4096];
 	unsigned int i;
 	unsigned long flags;
 
-	memset(iodc_dbuf, 0, 4096);
-	for (i = 0; i < count && i < 2048;) {
+	for (i = 0; i < count && i < 79;) {
 		switch(str[i]) {
 		case '\n':
 			iodc_dbuf[i+0] = '\r';
 			iodc_dbuf[i+1] = '\n';
 			i += 2;
 			posx = 0;
-			break;
+			goto print;
 		case '\t':
 			while (posx & 7) {
 				iodc_dbuf[i] = ' ';
@@ -1124,6 +1123,16 @@ int pdc_iodc_print(unsigned char *str, unsigned count)
 		}
 	}
 
+	/* if we're at the end of line, and not already inserting a newline,
+	 * insert one anyway. iodc console doesn't claim to support >79 char
+	 * lines. don't account for this in the return value.
+	 */
+	if (i == 79 && iodc_dbuf[i-1] != '\n') {
+		iodc_dbuf[i+0] = '\r';
+		iodc_dbuf[i+1] = '\n';
+	}
+
+print:
         spin_lock_irqsave(&pdc_lock, flags);
         real32_call(PAGE0->mem_cons.iodc_io,
                     (unsigned long)PAGE0->mem_cons.hpa, ENTRY_IO_COUT,
@@ -1142,11 +1151,9 @@ int pdc_iodc_print(unsigned char *str, unsigned count)
  */
 int pdc_iodc_getc(void)
 {
-	unsigned long flags;
-        static int __attribute__((aligned(8)))   iodc_retbuf[32];
-        static char __attribute__((aligned(64))) iodc_dbuf[4096];
 	int ch;
 	int status;
+	unsigned long flags;
 
 	/* Bail if no console input device. */
 	if (!PAGE0->mem_kbd.iodc_io)
diff --git a/arch/parisc/kernel/pdc_cons.c b/arch/parisc/kernel/pdc_cons.c
index 33b1f84..7f471a4 100644
--- a/arch/parisc/kernel/pdc_cons.c
+++ b/arch/parisc/kernel/pdc_cons.c
@@ -52,10 +52,18 @@
 #include <linux/tty.h>
 #include <asm/pdc.h>		/* for iodc_call() proto and friends */
 
+static spinlock_t pdc_console_lock = SPIN_LOCK_UNLOCKED;
 
 static void pdc_console_write(struct console *co, const char *s, unsigned count)
 {
-	pdc_iodc_print(s, count);
+	int i = 0;
+	unsigned long flags;
+
+	spin_lock_irqsave(&pdc_console_lock, flags);
+	do {
+		i += pdc_iodc_print(s + i, count - i);
+	} while (i < count);
+	spin_unlock_irqrestore(&pdc_console_lock, flags);
 }
 
 void pdc_printf(const char *fmt, ...)
@@ -73,7 +81,14 @@ void pdc_printf(const char *fmt, ...)
 
 int pdc_console_poll_key(struct console *co)
 {
-	return pdc_iodc_getc();
+	int c;
+	unsigned long flags;
+
+	spin_lock_irqsave(&pdc_console_lock, flags);
+	c = pdc_iodc_getc();
+	spin_unlock_irqrestore(&pdc_console_lock, flags);
+
+	return c;
 }
 
 static int pdc_console_setup(struct console *co, char *options)
diff --git a/include/asm-parisc/pdc.h b/include/asm-parisc/pdc.h
index deda8c3..9eaa794 100644
--- a/include/asm-parisc/pdc.h
+++ b/include/asm-parisc/pdc.h
@@ -645,8 +645,7 @@ int pdc_soft_power_button(int sw_control);
 void pdc_io_reset(void);
 void pdc_io_reset_devices(void);
 int pdc_iodc_getc(void);
-int pdc_iodc_print(unsigned char *str, unsigned count);
-void pdc_printf(const char *fmt, ...);
+int pdc_iodc_print(const unsigned char *str, unsigned count);
 
 void pdc_emergency_unlock(void);
 int pdc_sti_call(unsigned long func, unsigned long flags,
-- 
1.5.3.8