From 54c39e9ba3a93e3848ad8f9d082c39010cfc5e73 Mon Sep 17 00:00:00 2001 From: Thomas Petazzoni Date: Wed, 2 Jul 2014 15:16:32 +0200 Subject: [PATCH] mtd: nand: reduce the warning noise when the ECC is too weak In commit 67a9ad9b8a6f ("mtd: nand: Warn the user if the selected ECC strength is too weak"), a check was added to inform the user when the ECC used for a NAND device is weaker than the recommended ECC advertised by the NAND chip. However, the warning uses WARN_ON(), which has two undesirable side-effects: - It just prints to the kernel log the fact that there is a warning in this file, at this line, but it doesn't explain anything about the warning itself. - It dumps a stack trace which is very noisy, for something that the user is most likely not able to fix. If a certain ECC used by the kernel is weaker than the advertised one, it's most likely to make sure the kernel uses an ECC that is compatible with the one used by the bootloader, and changing the bootloader may not necessarily be easy. Therefore, normal users would not be able to do anything to fix this very noisy warning, and will have to suffer from it at every kernel boot. At least every time I see this stack trace in my kernel boot log, I wonder what new thing is broken, just to realize that it's once again this NAND ECC warning. Therefore, this commit turns: ------------[ cut here ]------------ WARNING: CPU: 0 PID: 1 at /home/thomas/projets/linux-2.6/drivers/mtd/nand/nand_base.c:4051 nand_scan_tail+0x538/0x780() Modules linked in: CPU: 0 PID: 1 Comm: swapper Not tainted 3.16.0-rc3-dirty #4 [] (unwind_backtrace) from [] (show_stack+0x10/0x14) [] (show_stack) from [] (warn_slowpath_common+0x6c/0x8c) [] (warn_slowpath_common) from [] (warn_slowpath_null+0x1c/0x24) [] (warn_slowpath_null) from [] (nand_scan_tail+0x538/0x780) [] (nand_scan_tail) from [] (orion_nand_probe+0x224/0x2e4) [] (orion_nand_probe) from [] (platform_drv_probe+0x18/0x4c) [] (platform_drv_probe) from [] (really_probe+0x80/0x218) [] (really_probe) from [] (__driver_attach+0x98/0x9c) [] (__driver_attach) from [] (bus_for_each_dev+0x64/0x94) [] (bus_for_each_dev) from [] (bus_add_driver+0x144/0x1ec) [] (bus_add_driver) from [] (driver_register+0x78/0xf8) [] (driver_register) from [] (platform_driver_probe+0x20/0xb8) [] (platform_driver_probe) from [] (do_one_initcall+0x80/0x1d8) [] (do_one_initcall) from [] (kernel_init_freeable+0xf4/0x1b4) [] (kernel_init_freeable) from [] (kernel_init+0x8/0xec) [] (kernel_init) from [] (ret_from_fork+0x14/0x24) ---[ end trace 62f87d875aceccb4 ]--- Into the much shorter, and much more useful: nand: WARNING: MT29F2G08ABAEAWP: the ECC used on your system is too weak compared to the one required by the NAND chip Signed-off-by: Thomas Petazzoni Signed-off-by: Brian Norris --- drivers/mtd/nand/nand_base.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/drivers/mtd/nand/nand_base.c b/drivers/mtd/nand/nand_base.c index 41167e9e991e..4f3e80c68a26 100644 --- a/drivers/mtd/nand/nand_base.c +++ b/drivers/mtd/nand/nand_base.c @@ -4047,8 +4047,10 @@ int nand_scan_tail(struct mtd_info *mtd) ecc->layout->oobavail += ecc->layout->oobfree[i].length; mtd->oobavail = ecc->layout->oobavail; - /* ECC sanity check: warn noisily if it's too weak */ - WARN_ON(!nand_ecc_strength_good(mtd)); + /* ECC sanity check: warn if it's too weak */ + if (!nand_ecc_strength_good(mtd)) + pr_warn("WARNING: %s: the ECC used on your system is too weak compared to the one required by the NAND chip\n", + mtd->name); /* * Set the number of read / write steps for one page depending on ECC -- 2.30.2