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Subject[PATCH 6/8] block: sed-opal: split generation of bytestring header and content
Date
Split the header generation from the (normal) memcpy part if a
bytestring is copied into the command buffer. This allows in-place
generation of the bytestring content. For example, copy_from_user may be
used without an intermediate buffer.

Signed-off-by: Jonas Rabenstein <jonas.rabenstein@studium.uni-erlangen.de>
---
block/sed-opal.c | 23 +++++++++++++++--------
1 file changed, 15 insertions(+), 8 deletions(-)

diff --git a/block/sed-opal.c b/block/sed-opal.c
index f7925e6f607c..f169e621279a 100644
--- a/block/sed-opal.c
+++ b/block/sed-opal.c
@@ -584,14 +584,11 @@ static void add_token_u64(int *err, struct opal_dev *cmd, u64 number)
}
}

-static void add_token_bytestring(int *err, struct opal_dev *cmd,
- const u8 *bytestring, size_t len)
+static u8 *add_bytestring_header(int *err, struct opal_dev *cmd, size_t len)
{
size_t header_len = 1;
bool is_short_atom = true;
-
- if (*err)
- return;
+ char *start;

if (len & ~SHORT_ATOM_LEN_MASK) {
header_len = 2;
@@ -600,17 +597,27 @@ static void add_token_bytestring(int *err, struct opal_dev *cmd,

if (!can_add(err, cmd, header_len + len)) {
pr_debug("Error adding bytestring: end of buffer.\n");
- return;
+ return NULL;
}

if (is_short_atom)
add_short_atom_header(cmd, true, false, len);
else
add_medium_atom_header(cmd, true, false, len);
-
- memcpy(&cmd->cmd[cmd->pos], bytestring, len);
+ start = &cmd->cmd[cmd->pos];
cmd->pos += len;
+ return start;
+}

+static void add_token_bytestring(int *err, struct opal_dev *cmd,
+ const u8 *bytestring, size_t len)
+{
+ u8 *start;
+
+ start = add_bytestring_header(err, cmd, len);
+ if (!start)
+ return;
+ memcpy(start, bytestring, len);
}

static int build_locking_range(u8 *buffer, size_t length, u8 lr)
--
2.16.1
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