mtd: move zero length verification to MTD API functions

In many places in drivers we verify for the zero length, but this is very
inconsistent across drivers. This is obviously the right thing to do, though.
This patch moves the check to the MTD API functions instead and removes a lot
of duplication.

Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Reviewed-by: Shmulik Ladkani <shmulik.ladkani@gmail.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

1 files changed, 21 insertions, 0 deletions

diff --git a/drivers/mtd/mtdcore.c b/drivers/mtd/mtdcore.c
index b20346e9fecb..6acc4fb254e2 100644
--- a/drivers/mtd/mtdcore.c
+++ b/drivers/mtd/mtdcore.c
@@ -695,6 +695,11 @@ int mtd_erase(struct mtd_info *mtd, struct erase_info *instr)
                 return -EINVAL;
         if (!(mtd->flags & MTD_WRITEABLE))
                 return -EROFS;
+        if (!instr->len) {
+                instr->state = MTD_ERASE_DONE;
+                mtd_erase_callback(instr);
+                return 0;
+        }
         return mtd->_erase(mtd, instr);
 }
 EXPORT_SYMBOL_GPL(mtd_erase);
@@ -713,6 +718,8 @@ int mtd_point(struct mtd_info *mtd, loff_t from, size_t len, size_t *retlen,
                 return -EOPNOTSUPP;
         if (from < 0 || from > mtd->size || len > mtd->size - from)
                 return -EINVAL;
+        if (!len)
+                return 0;
         return mtd->_point(mtd, from, len, retlen, virt, phys);
 }
 EXPORT_SYMBOL_GPL(mtd_point);
@@ -724,6 +731,8 @@ int mtd_unpoint(struct mtd_info *mtd, loff_t from, size_t len)
                 return -EOPNOTSUPP;
         if (from < 0 || from > mtd->size || len > mtd->size - from)
                 return -EINVAL;
+        if (!len)
+                return 0;
         return mtd->_unpoint(mtd, from, len);
 }
 EXPORT_SYMBOL_GPL(mtd_unpoint);
@@ -750,6 +759,8 @@ int mtd_read(struct mtd_info *mtd, loff_t from, size_t len, size_t *retlen,
         *retlen = 0;
         if (from < 0 || from > mtd->size || len > mtd->size - from)
                 return -EINVAL;
+        if (!len)
+                return 0;
         return mtd->_read(mtd, from, len, retlen, buf);
 }
 EXPORT_SYMBOL_GPL(mtd_read);
@@ -762,6 +773,8 @@ int mtd_write(struct mtd_info *mtd, loff_t to, size_t len, size_t *retlen,
                 return -EINVAL;
         if (!mtd->_write || !(mtd->flags & MTD_WRITEABLE))
                 return -EROFS;
+        if (!len)
+                return 0;
         return mtd->_write(mtd, to, len, retlen, buf);
 }
 EXPORT_SYMBOL_GPL(mtd_write);
@@ -783,6 +796,8 @@ int mtd_panic_write(struct mtd_info *mtd, loff_t to, size_t len, size_t *retlen,
                 return -EINVAL;
         if (!(mtd->flags & MTD_WRITEABLE))
                 return -EROFS;
+        if (!len)
+                return 0;
         return mtd->_panic_write(mtd, to, len, retlen, buf);
 }
 EXPORT_SYMBOL_GPL(mtd_panic_write);
@@ -794,6 +809,8 @@ int mtd_lock(struct mtd_info *mtd, loff_t ofs, uint64_t len)
                 return -EOPNOTSUPP;
         if (ofs < 0 || ofs > mtd->size || len > mtd->size - ofs)
                 return -EINVAL;
+        if (!len)
+                return 0;
         return mtd->_lock(mtd, ofs, len);
 }
 EXPORT_SYMBOL_GPL(mtd_lock);
@@ -804,6 +821,8 @@ int mtd_unlock(struct mtd_info *mtd, loff_t ofs, uint64_t len)
                 return -EOPNOTSUPP;
         if (ofs < 0 || ofs > mtd->size || len > mtd->size - ofs)
                 return -EINVAL;
+        if (!len)
+                return 0;
         return mtd->_unlock(mtd, ofs, len);
 }
 EXPORT_SYMBOL_GPL(mtd_unlock);
@@ -814,6 +833,8 @@ int mtd_is_locked(struct mtd_info *mtd, loff_t ofs, uint64_t len)
                 return -EOPNOTSUPP;
         if (ofs < 0 || ofs > mtd->size || len > mtd->size - ofs)
                 return -EINVAL;
+        if (!len)
+                return 0;
         return mtd->_is_locked(mtd, ofs, len);
 }
 EXPORT_SYMBOL_GPL(mtd_is_locked);