mtd: Make sure the device supports erase operations in mtd_erase()

Some devices do not implement ->_erase() or have an invalid ->erasesize
value. In this case, mtd_erase() should return -ENOTSUPP.

Note that the test is not done on the MTD_NO_ERASE flag because this
flag means 'erasing a block before writing to it is unnecessary',
not 'the erase operation is not supported'. Actually, some drivers are
setting the MTD_NO_ERASE flag but still implementing the ->_erase()
hook and setting a valid ->erasesize value.

Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Reviewed-by: Miquel Raynal <miquel.raynal@free-electrons.com>
Signed-off-by: Boris Brezillon <boris.brezillon@bootlin.com>

1 files changed, 4 insertions, 0 deletions

diff --git a/drivers/mtd/mtdcore.c b/drivers/mtd/mtdcore.c
index 28553c840d32..56cb037a1052 100644
--- a/drivers/mtd/mtdcore.c
+++ b/drivers/mtd/mtdcore.c
@@ -971,10 +971,14 @@ EXPORT_SYMBOL_GPL(__put_mtd_device);
  */
 int mtd_erase(struct mtd_info *mtd, struct erase_info *instr)
 {
+        if (!mtd->erasesize || !mtd->_erase)
+                return -ENOTSUPP;
+
         if (instr->addr >= mtd->size || instr->len > mtd->size - instr->addr)
                 return -EINVAL;
         if (!(mtd->flags & MTD_WRITEABLE))
                 return -EROFS;
+
         instr->fail_addr = MTD_FAIL_ADDR_UNKNOWN;
         if (!instr->len) {
                 instr->state = MTD_ERASE_DONE;