UBI: allocate erase checking buffer on demand

Instead of using pre-allocated 'ubi->dbg_peb_buf' buffer in
'ubi_dbg_check_all_ff()', dynamically allocate it when needed. The
intend is to get rid of the pre-allocated 'ubi->dbg_peb_buf' buffer
completely. And the need for this arises because we want to change
to dynamic debugging control instead of compile-time control, i.e.,
we are going to kill the CONFIG_MTD_UBI_DEBUG_PARANOID Kconfig
option, which would mean that 'ubi->dbg_peb_buf' is always allocated,
which would be wasteful.

Thus, we are getting rid of 'ubi->dbg_peb_buf', and this is a
preparation for that.

signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>

1 files changed, 12 insertions, 7 deletions

diff --git a/drivers/mtd/ubi/io.c b/drivers/mtd/ubi/io.c
index b4d34ba60608..35da5aadbe10 100644
--- a/drivers/mtd/ubi/io.c
+++ b/drivers/mtd/ubi/io.c
@@ -1387,35 +1387,40 @@ int ubi_dbg_check_all_ff(struct ubi_device *ubi, int pnum, int offset, int len)
 {
         size_t read;
         int err;
+        void *buf;
         loff_t addr = (loff_t)pnum * ubi->peb_size + offset;
 
-        mutex_lock(&ubi->dbg_buf_mutex);
-        err = ubi->mtd->read(ubi->mtd, addr, len, &read, ubi->dbg_peb_buf);
+        buf = __vmalloc(len, GFP_KERNEL | GFP_NOFS, PAGE_KERNEL);
+        if (!buf) {
+                ubi_err("cannot allocate memory to check for 0xFFs");
+                return 0;
+        }
+
+        err = ubi->mtd->read(ubi->mtd, addr, len, &read, buf);
         if (err && err != -EUCLEAN) {
                 ubi_err("error %d while reading %d bytes from PEB %d:%d, "
                         "read %zd bytes", err, len, pnum, offset, read);
                 goto error;
         }
 
-        err = ubi_check_pattern(ubi->dbg_peb_buf, 0xFF, len);
+        err = ubi_check_pattern(buf, 0xFF, len);
         if (err == 0) {
                 ubi_err("flash region at PEB %d:%d, length %d does not "
                         "contain all 0xFF bytes", pnum, offset, len);
                 goto fail;
         }
-        mutex_unlock(&ubi->dbg_buf_mutex);
 
+        vfree(buf);
         return 0;
 
 fail:
         ubi_err("paranoid check failed for PEB %d", pnum);
         ubi_msg("hex dump of the %d-%d region", offset, offset + len);
-        print_hex_dump(KERN_DEBUG, "", DUMP_PREFIX_OFFSET, 32, 1,
-                       ubi->dbg_peb_buf, len, 1);
+        print_hex_dump(KERN_DEBUG, "", DUMP_PREFIX_OFFSET, 32, 1, buf, len, 1);
         err = -EINVAL;
 error:
         ubi_dbg_dump_stack();
-        mutex_unlock(&ubi->dbg_buf_mutex);
+        vfree(buf);
         return err;
 }