From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-qc0-x230.google.com ([2607:f8b0:400d:c01::230]) by merlin.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1WXohr-0002bG-Bo for linux-mtd@lists.infradead.org; Wed, 09 Apr 2014 09:22:08 +0000 Received: by mail-qc0-f176.google.com with SMTP id m20so2388542qcx.21 for ; Wed, 09 Apr 2014 02:21:43 -0700 (PDT) From: Helmut Schaa To: linux-mtd@lists.infradead.org Subject: [PATCH] mtd: nand: Disable subpage writes for drivers without ecc->hwctl Date: Wed, 9 Apr 2014 11:13:24 +0200 Message-Id: <1397034804-27161-1-git-send-email-helmut.schaa@googlemail.com> Cc: David Woodhouse , Artem Bityutskiy , Helmut Schaa , "Gupta, Pekon" List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , nand_write_subpage_hwecc causes a crash if the driver did not register ecc->hwctl or ecc->calculate. Fix this by disabling subpage writes if ecc->hwctl or ecc->calculate is not provided by the driver. This behavior was introduced in commit 837a6ba4f3b6d23026674e6af6b6849a4634fff9 "mtd: nand: subpage write support for hardware based ECC schemes". This fixes a crash with fsl_elbc_nand and maybe others: Unable to handle kernel paging request for instruction fetch Faulting instruction address: 0x00000000 Oops: Kernel access of bad area, sig: 11 [#1] SMP NR_CPUS=2 P1020 RDB Modules linked in: ath9k ath9k_common pppoe ppp_async option iptable_nat ath9k_hw ath usb_wwan pppox ppp_generic nf_nat_ipv4 nf_conntrack_ipv4 mac80211 ipt_MASQUERADE cfg80211 xt_time xt_tcpudp xt_state xt_quota xt_policy xt_pkttype xt_owner xt_nat xt_multiport xt_mh CPU: 1 PID: 2161 Comm: ubiformat Not tainted 3.10.26 #6 task: efbc2700 ti: c7950000 task.ti: c7950000 NIP: 00000000 LR: c01a495c CTR: 00000000 REGS: c7951cb0 TRAP: 0400 Not tainted (3.10.26) MSR: 00029000 CR: 24002028 XER: 00000000 GPR00: c01a4b6c c7951d60 efbc2700 ef84b000 00000001 00000000 000001ff c7800500 GPR08: 00000000 00000000 efae5e40 c01a4ae4 24002022 10023418 c7951e5c c7800500 GPR16: c017b6a8 00000000 0000003f c053404c 00000000 00000004 00000000 00000003 GPR24: 00000010 00000200 ef84b000 c7800d00 c7800000 c7800500 ef84b1c8 00000000 NIP [00000000] (null) LR [c01a495c] nand_write_subpage_hwecc+0x74/0x174 Call Trace: [c7951d60] [c7951d64] 0xc7951d64 (unreliable) [c7951da0] [c01a4b6c] nand_write_page+0x88/0x198 [c7951dd0] [c01a5f7c] nand_do_write_ops+0x2f4/0x39c [c7951e40] [c01a61e0] nand_write+0x58/0x84 [c7951e80] [c019e29c] mtdchar_write+0x1dc/0x28c [c7951ef0] [c00aba84] vfs_write+0xcc/0x1ac [c7951f10] [c00ac04c] SyS_write+0x4c/0x90 [c7951f40] [c000cd84] ret_from_syscall+0x0/0x3c --- Exception: c01 at 0x48050ed8 LR = 0x100071b8 Instruction dump: XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX ---[ end trace 161d3c65a2a15cb8 ]--- Kernel panic - not syncing: Fatal exception Cc: Gupta, Pekon Cc: Artem Bityutskiy Cc: David Woodhouse Signed-off-by: Helmut Schaa --- I noticed this bug on openwrt with kernel 3.10 but it looks as if this can still happen in more recent kernels. drivers/mtd/nand/nand_base.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/mtd/nand/nand_base.c b/drivers/mtd/nand/nand_base.c index 9715a7b..2298289 100644 --- a/drivers/mtd/nand/nand_base.c +++ b/drivers/mtd/nand/nand_base.c @@ -3768,7 +3768,7 @@ int nand_scan_tail(struct mtd_info *mtd) ecc->write_oob = nand_write_oob_std; if (!ecc->read_subpage) ecc->read_subpage = nand_read_subpage; - if (!ecc->write_subpage) + if (!ecc->write_subpage && ecc->hwctl && ecc->calculate) ecc->write_subpage = nand_write_subpage_hwecc; case NAND_ECC_HW_SYNDROME: -- 1.8.4.5