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>

diff --git a/drivers/mtd/ubi/io.c b/drivers/mtd/ubi/io.c
index b4d34ba6060886b5eeacc29cfc280057a8d5f002..35da5aadbe10fc01d46c97be8041cabdaad63c44 100644 (file)
--- 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;
 }