UBI: allocate write checking buffer on demand

Instead of using pre-allocated 'ubi->dbg_peb_buf' buffer in
'ubi_dbg_check_write()', 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>

2 files changed, 16 insertions, 9 deletions

diff --git a/drivers/mtd/ubi/io.c b/drivers/mtd/ubi/io.c
index 889e25c49323..b4d34ba60608 100644
--- a/drivers/mtd/ubi/io.c
+++ b/drivers/mtd/ubi/io.c
@@ -1326,16 +1326,22 @@ int ubi_dbg_check_write(struct ubi_device *ubi, const void *buf, int pnum,
 {
         int err, i;
         size_t read;
+        void *buf1;
         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);
+        buf1 = __vmalloc(len, GFP_KERNEL | GFP_NOFS, PAGE_KERNEL);
+        if (!buf1) {
+                ubi_err("cannot allocate memory to check writes");
+                return 0;
+        }
+
+        err = ubi->mtd->read(ubi->mtd, addr, len, &read, buf1);
         if (err && err != -EUCLEAN)
-                goto out_unlock;
+                goto out_free;
 
         for (i = 0; i < len; i++) {
                 uint8_t c = ((uint8_t *)buf)[i];
-                uint8_t c1 = ((uint8_t *)ubi->dbg_peb_buf)[i];
+                uint8_t c1 = ((uint8_t *)buf1)[i];
                 int dump_len;
 
                 if (c == c1)
@@ -1352,17 +1358,17 @@ int ubi_dbg_check_write(struct ubi_device *ubi, const void *buf, int pnum,
                 ubi_msg("hex dump of the read buffer from %d to %d",
                         i, i + dump_len);
                 print_hex_dump(KERN_DEBUG, "", DUMP_PREFIX_OFFSET, 32, 1,
-                               ubi->dbg_peb_buf + i, dump_len, 1);
+                               buf1 + i, dump_len, 1);
                 ubi_dbg_dump_stack();
                 err = -EINVAL;
-                goto out_unlock;
+                goto out_free;
         }
-        mutex_unlock(&ubi->dbg_buf_mutex);
 
+        vfree(buf1);
         return 0;
 
-out_unlock:
-        mutex_unlock(&ubi->dbg_buf_mutex);
+out_free:
+        vfree(buf1);
         return err;
 }
 
diff --git a/drivers/mtd/ubi/ubi.h b/drivers/mtd/ubi/ubi.h
index 0b0149c41fe3..9af362c2a137 100644
--- a/drivers/mtd/ubi/ubi.h
+++ b/drivers/mtd/ubi/ubi.h
@@ -40,6 +40,7 @@
 #include <linux/notifier.h>
 #include <linux/mtd/mtd.h>
 #include <linux/mtd/ubi.h>
+#include <asm/pgtable.h>
 
 #include "ubi-media.h"
 #include "scan.h"