linux-kernel - [PATCH 3.16 210/366] mtd: cfi: cmdset_0002: Do not allow read/write to suspend erase block.

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Message-ID: <lsq.1539530741.983404243@decadent.org.uk>
Date:   Sun, 14 Oct 2018 16:25:41 +0100
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org,
        "Boris Brezillon" <boris.brezillon@...tlin.com>,
        "Joakim Tjernlund" <joakim.tjernlund@...inera.com>,
        "Richard Weinberger" <richard@....at>
Subject: [PATCH 3.16 210/366] mtd: cfi: cmdset_0002: Do not allow
 read/write to suspend erase block.

3.16.60-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Joakim Tjernlund <joakim.tjernlund@...inera.com>

commit 7b70eb14392a7cf505f9b358d06c33b5af73d1e7 upstream.

Currently it is possible to read and/or write to suspend EB's.
Writing /dev/mtdX or /dev/mtdblockX from several processes may
break the flash state machine.

Taken from cfi_cmdset_0001 driver.

Signed-off-by: Joakim Tjernlund <joakim.tjernlund@...inera.com>
Reviewed-by: Richard Weinberger <richard@....at>
Signed-off-by: Boris Brezillon <boris.brezillon@...tlin.com>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 drivers/mtd/chips/cfi_cmdset_0002.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

--- a/drivers/mtd/chips/cfi_cmdset_0002.c
+++ b/drivers/mtd/chips/cfi_cmdset_0002.c
@@ -780,9 +780,10 @@ static int get_chip(struct map_info *map
 		    (mode == FL_WRITING && (cfip->EraseSuspend & 0x2))))
 			goto sleep;
 
-		/* We could check to see if we're trying to access the sector
-		 * that is currently being erased. However, no user will try
-		 * anything like that so we just wait for the timeout. */
+		/* Do not allow suspend iff read/write to EB address */
+		if ((adr & chip->in_progress_block_mask) ==
+		    chip->in_progress_block_addr)
+			goto sleep;
 
 		/* Erase suspend */
 		/* It's harmless to issue the Erase-Suspend and Erase-Resume
@@ -1926,6 +1927,7 @@ static int __xipram do_erase_chip(struct
 	chip->state = FL_ERASING;
 	chip->erase_suspended = 0;
 	chip->in_progress_block_addr = adr;
+	chip->in_progress_block_mask = ~(map->size - 1);
 
 	INVALIDATE_CACHE_UDELAY(map, chip,
 				adr, map->size,
@@ -2015,6 +2017,7 @@ static int __xipram do_erase_oneblock(st
 	chip->state = FL_ERASING;
 	chip->erase_suspended = 0;
 	chip->in_progress_block_addr = adr;
+	chip->in_progress_block_mask = ~(len - 1);
 
 	INVALIDATE_CACHE_UDELAY(map, chip,
 				adr, len,