Hi, Wang Nan
Rethinking about this patch, I still have several comments.
On 03/20/14 at 07:33am, Wang Nan wrote:
> This patch introduces setup_dtb_prop(), which is used for dtb
> operations. The code is extracted from zImage_arm_load, and this patch
> makes memory grown computation more accurate.
>
> Signed-off-by: Wang Nan <wangnan0 at huawei.com>
> Cc: Simon Horman <horms at verge.net.au>
> Cc: Dave Young <dyoung at redhat.com>
> Cc: Geng Hui <hui.geng at huawei.com>
> ---
> kexec/arch/arm/kexec-zImage-arm.c | 96 ++++++++++++++++++++++++++++-----------
> 1 file changed, 70 insertions(+), 26 deletions(-)
>
> diff --git a/kexec/arch/arm/kexec-zImage-arm.c b/kexec/arch/arm/kexec-zImage-arm.c
> index 8a35018..977254e 100644
> --- a/kexec/arch/arm/kexec-zImage-arm.c
> +++ b/kexec/arch/arm/kexec-zImage-arm.c
> @@ -216,6 +216,68 @@ int atag_arm_load(struct kexec_info *info, unsigned long base,
> return 0;
> }
>
> +static int setup_dtb_prop(char **bufp, off_t *sizep, const char *node_name,
> + const char *prop_name, const void *val, int len)
> +{
> + char *dtb_buf;
> + int off;
> +
> + if ((bufp == NULL) || (sizep == NULL) || (*bufp == NULL))
> + die("Internal error\n");
> +
> + dtb_buf = *bufp;
> +
> + /*
> + * Potential memory usage grown:
> + *
> + * 1. if fdt_add_subnode is called:
> + * sizeof(struct fdt_node_header) + FDT_TAGALIGN(nodename+1) + FDT_TAGSIZE
> + * // see fdt_add_subnode_namelen()
> + *
> + * 2. in fdt_setprop, if _fdt_add_property is called:
> + * a) strlen(prop_name) + 1 // see _fdt_find_add_string()
> + * b) sizeof(struct fdt_property) + FDT_TAGALIGN(len)
> + * // see _fdt_add_property()
> + *
> + * FDT_TAGALIGN is (FDT_ALIGN((x), FDT_TAGSIZE)), which is same
> + * to _ALIGN(x, FDT_TAGSIZE).
> + */
The comments are not necessary because it's obvious in the code itself.
Maybe add two functions in libfdt is better, such as node_len() and prop_len()
> +
> + *sizep = fdt_totalsize(*bufp) +
> + /* fdt_add_subnode -> fdt_add_subnode_namelen */
ditto.
> + sizeof(struct fdt_node_header) +
> + _ALIGN(strlen(node_name) + 1, FDT_TAGSIZE) +
> + FDT_TAGSIZE +
> + /* fdt_setprop -> _fdt_add_property -> _fdt_find_add_string */
ditto.
> + strlen(prop_name) + 1 +
> + /* fdt_setprop -> _fdt_add_property */
ditto.
OTOH, should not extend the dtb_buf with extra node size if the node exist.
same for the property
> + sizeof(struct fdt_property) + _ALIGN(len, FDT_TAGSIZE);
> +
> + dtb_buf = xrealloc(dtb_buf, *sizep);
> + if (dtb_buf == NULL)
> + die("xrealloc failed\n");
> + *bufp = dtb_buf;
> +
> + fdt_set_totalsize(dtb_buf, *sizep);
> +
> + /* check if the subnode already exists */
The comment is not necessary.
> + off = fdt_path_offset(dtb_buf, node_name);
> +
> + if (off == -FDT_ERR_NOTFOUND)
> + off = fdt_add_subnode(dtb_buf, off, node_name);
> + if (off < 0) {
> + fprintf(stderr, "FDT: Error adding %s node.\n", node_name);
> + return -1;
> + }
> + if (fdt_setprop(dtb_buf, off, prop_name,
> + val, len) != 0) {
> + fprintf(stderr, "FDT: Error setting %s/%s property.\n",
> + node_name, prop_name);
> + return -1;
> + }
> + return 0;
> +}
> +
> int zImage_arm_load(int argc, char **argv, const char *buf, off_t len,
> struct kexec_info *info)
> {
> @@ -375,32 +437,14 @@ int zImage_arm_load(int argc, char **argv, const char *buf, off_t len,
> }
>
> if (command_line) {
> - const char *node_name = "/chosen";
> - const char *prop_name = "bootargs";
> - int off;
> -
> - dtb_length = fdt_totalsize(dtb_buf) + 1024 +
> - strlen(command_line);
> - dtb_buf = xrealloc(dtb_buf, dtb_length);
> - fdt_set_totalsize(dtb_buf, dtb_length);
> -
> - /* check if a /choosen subnode already exists */
> - off = fdt_path_offset(dtb_buf, node_name);
> -
> - if (off == -FDT_ERR_NOTFOUND)
> - off = fdt_add_subnode(dtb_buf, off, node_name);
> -
> - if (off < 0) {
> - fprintf(stderr, "FDT: Error adding %s node.\n", node_name);
> - return -1;
> - }
> -
> - if (fdt_setprop(dtb_buf, off, prop_name,
> - command_line, strlen(command_line) + 1) != 0) {
> - fprintf(stderr, "FDT: Error setting %s/%s property.\n",
> - node_name, prop_name);
> - return -1;
> - }
> + /*
> + * Error should have been reported so
> + * directly return -1
> + */
> + if (setup_dtb_prop(&dtb_buf, &dtb_length, "/chosen",
> + "bootargs", command_line,
> + strlen(command_line) + 1))
> + return -1;
> }
> } else {
> /*
> --
> 1.8.3.4
>
>
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