[patch] cfi: prevent kernel panic with cfi flash

[patch] cfi: prevent kernel panic with cfi flash

[Jan Pedersen]

When using the cfi (common flash interface) driver, every word written to
the flash chips is followed by a operation complete poll. This poll is
intended to have a timeout of 1 ms. However this timeout is calculated by
HZ/1000, which happends to be 0 because HZ < 1000. The result of this is
that there will be just one poll for operation complete. If this single poll
fails, the kernel panics. This patch increases this timeout to HZ (1
second). This is far more than needed, but is preferred over a panic. This
fix is well tested and completely avoids the panic.

Signed-off-by: Jan Pedersen <jp@jp-embedded.com>
---
diff -Naur linux-2.4.31.org/drivers/mtd/chips/cfi_cmdset_0002.c
linux-2.4.31/drivers/mtd/chips/cfi_cmdset_0002.c
--- linux-2.4.31.org/drivers/mtd/chips/cfi_cmdset_0002.c	2004-11-17
06:54:21.000000000 -0500
+++ linux-2.4.31/drivers/mtd/chips/cfi_cmdset_0002.c	2005-08-22
12:14:17.000000000 -0400
@@ -510,7 +510,7 @@
 	   or tells us why it failed. */        
 	dq6 = CMD(1<<6);
 	dq5 = CMD(1<<5);
-	timeo = jiffies + (HZ/1000); /* setting timeout to 1ms for now */
+	timeo = jiffies + (HZ); /* setting timeout to 1s for now */
 		
 	oldstatus = cfi_read(map, adr);
 	status = cfi_read(map, adr);

[patch] cfi: prevent kernel panic with cfi flash

[Jan Pedersen]

When using the cfi (common flash interface) driver, every word written to
the flash chips is followed by a operation complete poll. This poll is
intended to have a timeout of 1 ms. However this timeout is calculated by
HZ/1000, which happends to be 0 because HZ < 1000. The result of this is
that there will be just one poll for operation complete. If this single poll
fails, the kernel panics. This patch increases this timeout to HZ (1
second). This is far more than needed, but is preferred over a panic. This
fix is well tested and completely avoids the panic.

Signed-off-by: Jan Pedersen <jp@jp-embedded.com>
---
diff -Naur linux-2.4.31.org/drivers/mtd/chips/cfi_cmdset_0002.c
linux-2.4.31/drivers/mtd/chips/cfi_cmdset_0002.c
--- linux-2.4.31.org/drivers/mtd/chips/cfi_cmdset_0002.c	2004-11-17
06:54:21.000000000 -0500
+++ linux-2.4.31/drivers/mtd/chips/cfi_cmdset_0002.c	2005-08-22
12:14:17.000000000 -0400
@@ -510,7 +510,7 @@
 	   or tells us why it failed. */        
 	dq6 = CMD(1<<6);
 	dq5 = CMD(1<<5);
-	timeo = jiffies + (HZ/1000); /* setting timeout to 1ms for now */
+	timeo = jiffies + (HZ); /* setting timeout to 1s for now */
 		
 	oldstatus = cfi_read(map, adr);
 	status = cfi_read(map, adr);

Re: [patch] cfi: prevent kernel panic with cfi flash

[Ralf Baechle]

On Tue, Sep 27, 2005 at 09:25:42PM +0200, Jan Pedersen wrote:

> When using the cfi (common flash interface) driver, every word written to
> the flash chips is followed by a operation complete poll. This poll is
> intended to have a timeout of 1 ms. However this timeout is calculated by
> HZ/1000, which happends to be 0 because HZ < 1000. The result of this is
> that there will be just one poll for operation complete. If this single poll
> fails, the kernel panics. This patch increases this timeout to HZ (1
> second). This is far more than needed, but is preferred over a panic. This
> fix is well tested and completely avoids the panic.
> 
> Signed-off-by: Jan Pedersen <jp@jp-embedded.com>

Patch looks good to me - but this code isn't maintained by linux-mips.org,
so you may want to resend your patches here:

MEMORY TECHNOLOGY DEVICES
P:      David Woodhouse
M:      dwmw2@infradead.org
W:      http://www.linux-mtd.infradead.org/
L:      linux-mtd@lists.infradead.org
S:      Maintained

Thanks anyway,

  Ralf