This helper function gives us a way to read a header object and the subsequent payload from the checkpoint stream directly into our own buffer. This is used by the net/checkpoint.c code to read skb's without a memcpy().
I'm sending this separately so that it doesn't get mixed in with the set going to netdev in a minute. Signed-off-by: Dan Smith <[email protected]> --- checkpoint/restart.c | 36 ++++++++++++++++++++++++++++++++++-- include/linux/checkpoint.h | 4 ++++ 2 files changed, 38 insertions(+), 2 deletions(-) diff --git a/checkpoint/restart.c b/checkpoint/restart.c index 4155426..3bfee31 100644 --- a/checkpoint/restart.c +++ b/checkpoint/restart.c @@ -177,6 +177,38 @@ int _ckpt_read_string(struct ckpt_ctx *ctx, void *ptr, int len) } /** + * _ckpt_read_hdr_type - read a header record and check the type + * @ctx: checkpoint context + * @h: provided header buffer (returned) + * @type: optional type, 0 to ignore + * + * Returns the size of the payload to follow or negative on error + */ +int _ckpt_read_hdr_type(struct ckpt_ctx *ctx, struct ckpt_hdr *h, int type) +{ + int ret; + + ret = ckpt_kread(ctx, h, sizeof(*h)); + if (ret < 0) + return ret; + else if (type && h->type != type) + return -EINVAL; + else + return h->len - sizeof(*h); +} + +/** + * _ckpt_read_payload - read the payload associated with a recent header read + * @ctx: checkpoint_context + * @h: header returned from _ckpt_read_hdr_type() + * @buffer: pre-allocated buffer to store payload + */ +int _ckpt_read_payload(struct ckpt_ctx *ctx, struct ckpt_hdr *h, void *buffer) +{ + return ckpt_kread(ctx, buffer, h->len - sizeof(*h)); +} + +/** * ckpt_read_obj - allocate and read an object (ckpt_hdr followed by payload) * @ctx: checkpoint context * @h: object descriptor @@ -192,7 +224,7 @@ static void *ckpt_read_obj(struct ckpt_ctx *ctx, int len, int max) int ret; again: - ret = ckpt_kread(ctx, &hh, sizeof(hh)); + ret = _ckpt_read_hdr_type(ctx, &hh, 0); if (ret < 0) return ERR_PTR(ret); _ckpt_debug(CKPT_DRW, "type %d len %d(%d,%d)\n", @@ -217,7 +249,7 @@ static void *ckpt_read_obj(struct ckpt_ctx *ctx, int len, int max) *h = hh; /* yay ! */ - ret = ckpt_kread(ctx, (h + 1), hh.len - sizeof(struct ckpt_hdr)); + ret = _ckpt_read_payload(ctx, &hh, (h + 1)); if (ret < 0) { ckpt_hdr_put(ctx, h); h = ERR_PTR(ret); diff --git a/include/linux/checkpoint.h b/include/linux/checkpoint.h index 2765c33..ccc4aab 100644 --- a/include/linux/checkpoint.h +++ b/include/linux/checkpoint.h @@ -63,6 +63,10 @@ extern int ckpt_write_string(struct ckpt_ctx *ctx, char *str, int len); extern void __ckpt_write_err(struct ckpt_ctx *ctx, char *fmt, ...); extern int ckpt_write_err(struct ckpt_ctx *ctx, char *fmt, ...); +extern int _ckpt_read_payload(struct ckpt_ctx *ctx, struct ckpt_hdr *h, + void *buffer); +extern int _ckpt_read_hdr_type(struct ckpt_ctx *ctx, struct ckpt_hdr *h, + int type); extern int _ckpt_read_obj_type(struct ckpt_ctx *ctx, void *ptr, int len, int type); extern int _ckpt_read_nbuffer(struct ckpt_ctx *ctx, void *ptr, int len); -- 1.6.2.2 _______________________________________________ Containers mailing list [email protected] https://lists.linux-foundation.org/mailman/listinfo/containers _______________________________________________ Devel mailing list [email protected] https://openvz.org/mailman/listinfo/devel
