diff mbox series

fw_env: keep calling read() until whole flash block is read

Message ID 20231213121354.13303-1-zajec5@gmail.com
State Accepted
Commit 9e3003f79d168eac7ee65cd457e3904e2fb4eea8
Delegated to: Tom Rini
Headers show
Series fw_env: keep calling read() until whole flash block is read | expand

Commit Message

Rafał Miłecki Dec. 13, 2023, 12:13 p.m. UTC 
From: Rafał Miłecki <rafal@milecki.pl>

It's totally valid for read() to provide less bytes than requested
maximum. It may happen if there is no more data available yet or source
pushes data in small chunks.

This actually happens when trying to read env data from NVMEM device.
Kernel may provide NVMEM content in page size parts (like 4096 B).

This fixes warnings like:
Warning on /sys/bus/nvmem/devices/u-boot-env0/nvmem: Attempted to read 16384 bytes but got 4096
Warning on /sys/bus/nvmem/devices/u-boot-env0/nvmem: Attempted to read 12288 bytes but got 4096
Warning on /sys/bus/nvmem/devices/u-boot-env0/nvmem: Attempted to read 8192 bytes but got 4096

Since the main loop in flash_read_buf() is used to read blocks this
patch adds a new nested one.

Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
---
 tools/env/fw_env.c | 34 +++++++++++++++-------------------
 1 file changed, 15 insertions(+), 19 deletions(-)

Comments

Tom Rini Jan. 6, 2024, 5:41 p.m. UTC | #1 
On Wed, Dec 13, 2023 at 01:13:54PM +0100, Rafał Miłecki wrote:

> From: Rafał Miłecki <rafal@milecki.pl>
> 
> It's totally valid for read() to provide less bytes than requested
> maximum. It may happen if there is no more data available yet or source
> pushes data in small chunks.
> 
> This actually happens when trying to read env data from NVMEM device.
> Kernel may provide NVMEM content in page size parts (like 4096 B).
> 
> This fixes warnings like:
> Warning on /sys/bus/nvmem/devices/u-boot-env0/nvmem: Attempted to read 16384 bytes but got 4096
> Warning on /sys/bus/nvmem/devices/u-boot-env0/nvmem: Attempted to read 12288 bytes but got 4096
> Warning on /sys/bus/nvmem/devices/u-boot-env0/nvmem: Attempted to read 8192 bytes but got 4096
> 
> Since the main loop in flash_read_buf() is used to read blocks this
> patch adds a new nested one.
> 
> Signed-off-by: Rafał Miłecki <rafal@milecki.pl>

Applied to u-boot/next, thanks!
diff mbox series

Patch

diff --git a/tools/env/fw_env.c b/tools/env/fw_env.c
index 0347e9d15a..90010dabd8 100644
--- a/tools/env/fw_env.c
+++ b/tools/env/fw_env.c
@@ -948,29 +948,25 @@  static int flash_read_buf(int dev, int fd, void *buf, size_t count,
 		 */
 		lseek(fd, blockstart + block_seek, SEEK_SET);
 
-		rc = read(fd, buf + processed, readlen);
-		if (rc == -1) {
-			fprintf(stderr, "Read error on %s: %s\n",
-				DEVNAME(dev), strerror(errno));
-			return -1;
-		}
+		while (readlen) {
+			rc = read(fd, buf + processed, readlen);
+			if (rc == -1) {
+				fprintf(stderr, "Read error on %s: %s\n",
+					DEVNAME(dev), strerror(errno));
+				return -1;
+			}
 #ifdef DEBUG
-		fprintf(stderr, "Read 0x%x bytes at 0x%llx on %s\n",
-			rc, (unsigned long long)blockstart + block_seek,
-			DEVNAME(dev));
+			fprintf(stderr, "Read 0x%x bytes at 0x%llx on %s\n",
+				rc, (unsigned long long)blockstart + block_seek,
+				DEVNAME(dev));
 #endif
-		processed += rc;
-		if (rc != readlen) {
-			fprintf(stderr,
-				"Warning on %s: Attempted to read %zd bytes but got %d\n",
-				DEVNAME(dev), readlen, rc);
+			processed += rc;
 			readlen -= rc;
-			block_seek += rc;
-		} else {
-			blockstart += blocklen;
-			readlen = min(blocklen, count - processed);
-			block_seek = 0;
 		}
+
+		blockstart += blocklen;
+		readlen = min(blocklen, count - processed);
+		block_seek = 0;
 	}
 
 	return processed;