[PATCH v4 01/58] mtd: nand: denali: add missing nand_release() call in denali_remove()

Hi Brian,

On Thu, 10 Dec 2015 16:40:08 -0800
Brian Norris [off-list ref] wrote:

On Thu, Dec 10, 2015 at 08:59:45AM +0100, Boris Brezillon wrote:

quoted

Unregister the NAND device from the NAND subsystem when removing a denali
NAND controller, otherwise the MTD attached to the NAND device is still
exposed by the MTD layer, and accesses to this device will likely crash
the system.

Signed-off-by: Boris Brezillon <redacted>
Cc: <redacted> #3.8+

Does this follow these rules, from
Documentation/stable_kernel_rules.txt?

 - It must be obviously correct and tested.

 - It must fix a real bug that bothers people (not a, "This could be a
   problem..." type thing).

As you wish, I'll remove those Cc and Fixes tags, or just drop the
patch if you think it's useless...
I just noticed the bug while reworking this series, and thought it
would be useful to fix it, but I honestly don't care if it's applied
or not (I don't use this platform).

quoted

Fixes: 2a0a288ec258 ("mtd: denali: split the generic driver and PCI layer")
---
 drivers/mtd/nand/denali.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/mtd/nand/denali.c b/drivers/mtd/nand/denali.c
index 67eb2be..8feece3 100644
--- a/drivers/mtd/nand/denali.c
+++ b/drivers/mtd/nand/denali.c

@@ -1622,6 +1622,7 @@ EXPORT_SYMBOL(denali_init);
 /* driver exit point */
 void denali_remove(struct denali_nand_info *denali)
 {
+	nand_release(&denali->mtd);
 	denali_irq_cleanup(denali->irq, denali);
 	dma_unmap_single(denali->dev, denali->buf.dma_buf,
 			 denali->mtd.writesize + denali->mtd.oobsize,

It feels a bit odd to allow usage of MTD fields after it has been
unregistered. Maybe precompute this before the nand_release()?

nand_realease() is not releasing the mtd instance or re-initialazing
its field, so it should be safe, but I agree that pre-computing the DMA
buffer size is more future-proof.

I'll fix that, send a v5 and let you decide whether it's needed or not.

Best Regards,

Boris

-- 
Boris Brezillon, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com