linux-kernel - [PATCH 2/2] soc: qcom: cmd-db: Stop memcpy()ing in cmd_db_read_aux

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Date:   Tue, 17 Jul 2018 13:29:47 -0700
From:   Stephen Boyd <swboyd@...omium.org>
To:     Andy Gross <andy.gross@...aro.org>
Cc:     linux-kernel@...r.kernel.org, linux-arm-msm@...r.kernel.org,
        linux-soc@...r.kernel.org,
        Mahesh Sivasubramanian <msivasub@...eaurora.org>,
        Lina Iyer <ilina@...eaurora.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Evan Green <evgreen@...omium.org>
Subject: [PATCH 2/2] soc: qcom: cmd-db: Stop memcpy()ing in cmd_db_read_aux_data()

Let's change the function signature to return the pointer to memory or
an error pointer on failure, and take an argument that lets us return
the size of the aux data read. This way we can remove the
cmd_db_read_aux_data_len() API entirely and also get rid of the memcpy
operation from cmd_db to the caller.

Cc: Mahesh Sivasubramanian <msivasub@...eaurora.org>
Cc: Lina Iyer <ilina@...eaurora.org>
Cc: Bjorn Andersson <bjorn.andersson@...aro.org>
Cc: Evan Green <evgreen@...omium.org>
Signed-off-by: Stephen Boyd <swboyd@...omium.org>
---
 drivers/soc/qcom/cmd-db.c | 43 ++++++++-------------------------------
 include/soc/qcom/cmd-db.h | 12 +++--------
 2 files changed, 11 insertions(+), 44 deletions(-)

diff --git a/drivers/soc/qcom/cmd-db.c b/drivers/soc/qcom/cmd-db.c
index 5c9cc6824891..c701b3b010f1 100644
--- a/drivers/soc/qcom/cmd-db.c
+++ b/drivers/soc/qcom/cmd-db.c
@@ -192,55 +192,28 @@ EXPORT_SYMBOL(cmd_db_read_addr);
 /**
  * cmd_db_read_aux_data() - Query command db for aux data.
  *
- *  @id: Resource to retrieve AUX Data on.
- *  @data: Data buffer to copy returned aux data to. Returns size on NULL
- *  @len: Caller provides size of data buffer passed in.
+ *  @id: Resource to retrieve AUX Data on
+ *  @len: size of data buffer returned
  *
- *  Return: size of data on success, errno otherwise
+ *  Return: pointer to data on success, error pointer otherwise
  */
-int cmd_db_read_aux_data(const char *id, u8 *data, size_t len)
+const void *cmd_db_read_aux_data(const char *id, size_t *len)
 {
 	int ret;
 	const struct entry_header *ent;
 	const struct rsc_hdr *rsc_hdr;
-	u16 ent_len;
-
-	if (!data)
-		return -EINVAL;
 
 	ret = cmd_db_get_header(id, &ent, &rsc_hdr);
 	if (ret)
-		return ret;
-
-	ent_len = le16_to_cpu(ent->len);
-	if (len < ent_len)
-		return -EINVAL;
+		return ERR_PTR(ret);
 
-	len = min_t(u16, ent_len, len);
-	memcpy(data, rsc_offset(rsc_hdr, ent), len);
+	if (len)
+		*len = le16_to_cpu(ent->len);
 
-	return len;
+	return rsc_offset(rsc_hdr, ent);
 }
 EXPORT_SYMBOL(cmd_db_read_aux_data);
 
-/**
- * cmd_db_read_aux_data_len - Get the length of the auxiliary data stored in DB.
- *
- * @id: Resource to retrieve AUX Data.
- *
- * Return: size on success, 0 on error
- */
-size_t cmd_db_read_aux_data_len(const char *id)
-{
-	int ret;
-	const struct entry_header *ent;
-
-	ret = cmd_db_get_header(id, &ent, NULL);
-
-	return ret < 0 ? 0 : le16_to_cpu(ent->len);
-}
-EXPORT_SYMBOL(cmd_db_read_aux_data_len);
-
 /**
  * cmd_db_read_slave_id - Get the slave ID for a given resource address
  *
diff --git a/include/soc/qcom/cmd-db.h b/include/soc/qcom/cmd-db.h
index 578180cbc134..af9722223925 100644
--- a/include/soc/qcom/cmd-db.h
+++ b/include/soc/qcom/cmd-db.h
@@ -18,9 +18,7 @@ enum cmd_db_hw_type {
 #if IS_ENABLED(CONFIG_QCOM_COMMAND_DB)
 u32 cmd_db_read_addr(const char *resource_id);
 
-int cmd_db_read_aux_data(const char *resource_id, u8 *data, size_t len);
-
-size_t cmd_db_read_aux_data_len(const char *resource_id);
+const void *cmd_db_read_aux_data(const char *resource_id, size_t *len);
 
 enum cmd_db_hw_type cmd_db_read_slave_id(const char *resource_id);
 
@@ -29,12 +27,8 @@ int cmd_db_ready(void);
 static inline u32 cmd_db_read_addr(const char *resource_id)
 { return 0; }
 
-static inline int cmd_db_read_aux_data(const char *resource_id, u8 *data,
-				       size_t len)
-{ return -ENODEV; }
-
-static inline size_t cmd_db_read_aux_data_len(const char *resource_id)
-{ return -ENODEV; }
+static inline const void *cmd_db_read_aux_data(const char *resource_id, size_t *len)
+{ return ERR_PTR(-ENODEV); }
 
 static inline enum cmd_db_hw_type cmd_db_read_slave_id(const char *resource_id)
 { return -ENODEV; }
-- 
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