On 2020/12/8 2:59, Vignesh Raghavendra wrote:
Hi Xiaoming,
On 12/7/20 4:23 PM, Miquel Raynal wrote:
Hi Xiaoming,
Xiaoming Ni <nixiaoming@xxxxxxxxxx> wrote on Mon, 7 Dec 2020 18:48:33
+0800:
ping
On 2020/11/27 21:07, Xiaoming Ni wrote:
When CONFIG_MTD_XIP=y, local_irq_disable() is called in xip_disable().
To avoid sleep in interrupt context, we need to call local_irq_enable()
before schedule().
The problem call stack is as follows:
bug1:
do_write_oneword_retry()
xip_disable()
local_irq_disable()
do_write_oneword_once()
schedule()
bug2:
do_write_buffer()
xip_disable()
local_irq_disable()
do_write_buffer_wait()
schedule()
bug3:
do_erase_chip()
xip_disable()
local_irq_disable()
schedule()
bug4:
do_erase_oneblock()
xip_disable()
local_irq_disable()
schedule()
Fixes: 02b15e343aee ("[MTD] XIP for AMD CFI flash.")
Cc: stable@xxxxxxxxxxxxxxx # v2.6.13
Signed-off-by: Xiaoming Ni <nixiaoming@xxxxxxxxxx>
---
drivers/mtd/chips/cfi_cmdset_0002.c | 16 ++++++++++++++++
1 file changed, 16 insertions(+)
diff --git a/drivers/mtd/chips/cfi_cmdset_0002.c b/drivers/mtd/chips/cfi_cmdset_0002.c
index a1f3e1031c3d..12c3776f093a 100644
--- a/drivers/mtd/chips/cfi_cmdset_0002.c
+++ b/drivers/mtd/chips/cfi_cmdset_0002.c
@@ -1682,7 +1682,11 @@ static int __xipram do_write_oneword_once(struct map_info *map,
set_current_state(TASK_UNINTERRUPTIBLE);
add_wait_queue(&chip->wq, &wait);
mutex_unlock(&chip->mutex);
+ if (IS_ENABLED(CONFIG_MTD_XIP))
+ local_irq_enable();
schedule();
+ if (IS_ENABLED(CONFIG_MTD_XIP))
+ local_irq_disable();
The fix really seems strange to me. I will let Vignesh decide but I
think we should consider updating/fixing xip_disable instead.
Agree with Miquel. Have you done any testing
or is this purely based on code inspection?
I don't have the corresponding device test environment.
I found the problem through code review.
What about comment before xip_disable() function:
/*
* No interrupt what so ever can be serviced while the flash isn't in array
* mode. This is ensured by the xip_disable() and xip_enable() functions
* enclosing any code path where the flash is known not to be in array mode.
* And within a XIP disabled code path, only functions marked with __xipram
* may be called and nothing else (it's a good thing to inspect generated
* assembly to make sure inline functions were actually inlined and that gcc
* didn't emit calls to its own support functions). Also configuring MTD CFI
* support to a single buswidth and a single interleave is also recommended.
*/
So, I don't think the fix is as simple as this patch.
+xip_enable();
schedule();
+xip_disable();
Do I need to change it to this?
Regards
Vignesh
.
Thanks
Xiaoming Ni
