Modify fw_printenv to read in chunks of 0x20 at a time.
Signed-off-by: Joe Hershberger <[email protected]>
---
tools/env/fw_env.c | 25 ++++++++++++++++++++-----
1 file changed, 20 insertions(+), 5 deletions(-)
diff --git a/tools/env/fw_env.c b/tools/env/fw_env.c
index 8bb7f9a..9ecc22a 100644
--- a/tools/env/fw_env.c
+++ b/tools/env/fw_env.c
@@ -45,6 +45,8 @@
#include "fw_env.h"
+#define MAX_BYTES_PER_READ 0x20
+
#define WHITESPACE(c) ((c == '\t') || (c == ' '))
#define min(x, y) ({ \
@@ -671,6 +673,7 @@ static int flash_read_buf (int dev, int fd, void *buf,
size_t count,
size_t blocklen; /* erase / write length - one block on NAND,
0 on NOR */
size_t processed = 0; /* progress counter */
+ size_t bytesread = 0; /* bytes read so far */
size_t readlen = count; /* current read length */
off_t top_of_range; /* end of the last block we may use */
off_t block_seek; /* offset inside the current block to the start
@@ -730,11 +733,23 @@ 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 != readlen) {
- fprintf (stderr, "Read error on %s: %s\n",
- DEVNAME (dev), strerror (errno));
- return -1;
+ /*
+ * Break reads up into very small chunks so fw_printenv doesn't
+ * block the kernel long enough to starve other kernel tasks.
+ */
+ bytesread = 0;
+ while (bytesread < readlen) {
+ size_t bytestoread = readlen - bytesread;
+
+ if (bytestoread > MAX_BYTES_PER_READ)
+ bytestoread = MAX_BYTES_PER_READ;
+ rc = read(fd, buf + processed + bytesread, bytestoread);
+ if (rc != bytestoread) {
+ fprintf(stderr, "Read error on %s: %s\n",
+ DEVNAME(dev), strerror(errno));
+ return -1;
+ }
+ bytesread += bytestoread;
}
#ifdef DEBUG
fprintf (stderr, "Read 0x%x bytes at 0x%llx\n",
--
1.7.11.5
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