From fdf6760cda15b2710287c66c9969a3ed527793d8 Mon Sep 17 00:00:00 2001 From: Mathias Kresin Date: Sun, 8 Jul 2018 01:38:08 +0200 Subject: [PATCH] kernel: improve ubi auto attach code readability Move the put_mtd_device() called on multiple error conditions to a goto label to use it later for more error conditions. The early return on failed open of the mtd device and mismatching mtd type allows to get rid of one level of indentation. By jumping to the cleanup code, a refcount bug is fixed for the wrong flash type condition. While at it, make clear that we only check for the UBI magic if the read from flash was successful. Signed-off-by: Mathias Kresin --- ...mtd-device-named-ubi-or-data-on-boot.patch | 57 ++++++++++--------- ...mtd-device-named-ubi-or-data-on-boot.patch | 57 ++++++++++--------- 2 files changed, 62 insertions(+), 52 deletions(-) diff --git a/target/linux/generic/pending-4.14/490-ubi-auto-attach-mtd-device-named-ubi-or-data-on-boot.patch b/target/linux/generic/pending-4.14/490-ubi-auto-attach-mtd-device-named-ubi-or-data-on-boot.patch index 63afabb1d9..aa4dc12201 100644 --- a/target/linux/generic/pending-4.14/490-ubi-auto-attach-mtd-device-named-ubi-or-data-on-boot.patch +++ b/target/linux/generic/pending-4.14/490-ubi-auto-attach-mtd-device-named-ubi-or-data-on-boot.patch @@ -8,7 +8,7 @@ Signed-off-by: Daniel Golle --- a/drivers/mtd/ubi/build.c +++ b/drivers/mtd/ubi/build.c -@@ -1171,6 +1171,49 @@ static struct mtd_info * __init open_mtd +@@ -1171,6 +1171,54 @@ static struct mtd_info * __init open_mtd return mtd; } @@ -20,45 +20,50 @@ Signed-off-by: Daniel Golle +{ + int err; + struct mtd_info *mtd; ++ size_t len; ++ char magic[4]; + + /* try attaching mtd device named "ubi" or "data" */ + mtd = open_mtd_device("ubi"); + if (IS_ERR(mtd)) + mtd = open_mtd_device("data"); + -+ if (!IS_ERR(mtd)) { -+ size_t len; -+ char magic[4]; ++ if (IS_ERR(mtd)) ++ return; ++ ++ /* check for a valid ubi magic if read from flash was successful */ ++ err = mtd_read(mtd, 0, 4, &len, (void *) magic); ++ if (!err && len == 4 && strncmp(magic, "UBI#", 4)) { ++ pr_err("UBI error: no valid UBI magic found inside mtd%d\n", mtd->index); ++ goto cleanup; ++ } + -+ /* check for a valid ubi magic */ -+ err = mtd_read(mtd, 0, 4, &len, (void *) magic); -+ if (!err && len == 4 && strncmp(magic, "UBI#", 4)) { -+ pr_err("UBI error: no valid UBI magic found inside mtd%d\n", mtd->index); -+ put_mtd_device(mtd); -+ return; -+ } ++ /* don't auto-add media types where UBI doesn't makes sense */ ++ if (mtd->type != MTD_NANDFLASH && ++ mtd->type != MTD_NORFLASH && ++ mtd->type != MTD_DATAFLASH && ++ mtd->type != MTD_MLCNANDFLASH) ++ goto cleanup; + -+ /* auto-add only media types where UBI makes sense */ -+ if (mtd->type == MTD_NANDFLASH || -+ mtd->type == MTD_NORFLASH || -+ mtd->type == MTD_DATAFLASH || -+ mtd->type == MTD_MLCNANDFLASH) { -+ mutex_lock(&ubi_devices_mutex); -+ pr_notice("UBI: auto-attach mtd%d\n", mtd->index); -+ err = ubi_attach_mtd_dev(mtd, UBI_DEV_NUM_AUTO, 0, 0); -+ mutex_unlock(&ubi_devices_mutex); -+ if (err < 0) { -+ pr_err("UBI error: cannot attach mtd%d\n", mtd->index); -+ put_mtd_device(mtd); -+ } -+ } ++ mutex_lock(&ubi_devices_mutex); ++ pr_notice("UBI: auto-attach mtd%d\n", mtd->index); ++ err = ubi_attach_mtd_dev(mtd, UBI_DEV_NUM_AUTO, 0, 0); ++ mutex_unlock(&ubi_devices_mutex); ++ if (err < 0) { ++ pr_err("UBI error: cannot attach mtd%d\n", mtd->index); ++ goto cleanup; + } ++ ++ return; ++ ++cleanup: ++ put_mtd_device(mtd); +} + static int __init ubi_init(void) { int err, i, k; -@@ -1254,6 +1297,12 @@ static int __init ubi_init(void) +@@ -1254,6 +1302,12 @@ static int __init ubi_init(void) } } diff --git a/target/linux/generic/pending-4.9/490-ubi-auto-attach-mtd-device-named-ubi-or-data-on-boot.patch b/target/linux/generic/pending-4.9/490-ubi-auto-attach-mtd-device-named-ubi-or-data-on-boot.patch index 8b37dba034..1436e486dd 100644 --- a/target/linux/generic/pending-4.9/490-ubi-auto-attach-mtd-device-named-ubi-or-data-on-boot.patch +++ b/target/linux/generic/pending-4.9/490-ubi-auto-attach-mtd-device-named-ubi-or-data-on-boot.patch @@ -8,7 +8,7 @@ Signed-off-by: Daniel Golle --- a/drivers/mtd/ubi/build.c +++ b/drivers/mtd/ubi/build.c -@@ -1226,6 +1226,49 @@ static struct mtd_info * __init open_mtd +@@ -1226,6 +1226,54 @@ static struct mtd_info * __init open_mtd return mtd; } @@ -20,45 +20,50 @@ Signed-off-by: Daniel Golle +{ + int err; + struct mtd_info *mtd; ++ size_t len; ++ char magic[4]; + + /* try attaching mtd device named "ubi" or "data" */ + mtd = open_mtd_device("ubi"); + if (IS_ERR(mtd)) + mtd = open_mtd_device("data"); + -+ if (!IS_ERR(mtd)) { -+ size_t len; -+ char magic[4]; ++ if (IS_ERR(mtd)) ++ return; ++ ++ /* check for a valid ubi magic if read from flash was successful */ ++ err = mtd_read(mtd, 0, 4, &len, (void *) magic); ++ if (!err && len == 4 && strncmp(magic, "UBI#", 4)) { ++ pr_err("UBI error: no valid UBI magic found inside mtd%d\n", mtd->index); ++ goto cleanup; ++ } + -+ /* check for a valid ubi magic */ -+ err = mtd_read(mtd, 0, 4, &len, (void *) magic); -+ if (!err && len == 4 && strncmp(magic, "UBI#", 4)) { -+ pr_err("UBI error: no valid UBI magic found inside mtd%d\n", mtd->index); -+ put_mtd_device(mtd); -+ return; -+ } ++ /* don't auto-add media types where UBI doesn't makes sense */ ++ if (mtd->type != MTD_NANDFLASH && ++ mtd->type != MTD_NORFLASH && ++ mtd->type != MTD_DATAFLASH && ++ mtd->type != MTD_MLCNANDFLASH) ++ goto cleanup; + -+ /* auto-add only media types where UBI makes sense */ -+ if (mtd->type == MTD_NANDFLASH || -+ mtd->type == MTD_NORFLASH || -+ mtd->type == MTD_DATAFLASH || -+ mtd->type == MTD_MLCNANDFLASH) { -+ mutex_lock(&ubi_devices_mutex); -+ pr_notice("UBI: auto-attach mtd%d\n", mtd->index); -+ err = ubi_attach_mtd_dev(mtd, UBI_DEV_NUM_AUTO, 0, 0); -+ mutex_unlock(&ubi_devices_mutex); -+ if (err < 0) { -+ pr_err("UBI error: cannot attach mtd%d\n", mtd->index); -+ put_mtd_device(mtd); -+ } -+ } ++ mutex_lock(&ubi_devices_mutex); ++ pr_notice("UBI: auto-attach mtd%d\n", mtd->index); ++ err = ubi_attach_mtd_dev(mtd, UBI_DEV_NUM_AUTO, 0, 0); ++ mutex_unlock(&ubi_devices_mutex); ++ if (err < 0) { ++ pr_err("UBI error: cannot attach mtd%d\n", mtd->index); ++ goto cleanup; + } ++ ++ return; ++ ++cleanup: ++ put_mtd_device(mtd); +} + static int __init ubi_init(void) { int err, i, k; -@@ -1309,6 +1352,12 @@ static int __init ubi_init(void) +@@ -1309,6 +1357,12 @@ static int __init ubi_init(void) } } -- 2.30.2