[Devel] Re: [PATCH 1/7] move handling of err down into _ckpt_do_msg and _append
Oren Laadan
orenl at cs.columbia.edu
Mon Nov 16 11:25:47 PST 2009
Pulled for v19-rc1.
Oren.
serue at us.ibm.com wrote:
> From: Serge E. Hallyn <serue at us.ibm.com>
>
> Since ckpt_err() will also be used at restart, and since at
> restart we don't want to just set ctx->err, move handling of
> the argument 'err' further down. We only set ckpt->errno if
> err is not 0 and a checkpoint is going on. Then we automatically
> add '[err %d] % err' if err is non-0, so that the caller has a
> choice of passing in err or passing %(E) in fmt and err as a
> vararg.
>
> Changelog:
> nov 4: drop %(E) and print passed-in err instead
>
> Signed-off-by: Serge E. Hallyn <serue at us.ibm.com>
> ---
> checkpoint/sys.c | 51 +++++++++++++++++++++++++++----------------
> include/linux/checkpoint.h | 16 ++++++-------
> 2 files changed, 39 insertions(+), 28 deletions(-)
>
> diff --git a/checkpoint/sys.c b/checkpoint/sys.c
> index 7d14b30..c1c4e99 100644
> --- a/checkpoint/sys.c
> +++ b/checkpoint/sys.c
> @@ -382,14 +382,13 @@ static inline int is_special_flag(char *s)
> * The special flags are surrounded by %() to help them visually stand
> * out. For instance, %(O) means an objref. The following special
> * flags are recognized:
> - * E: error
> * O: objref
> * P: pointer
> * T: task
> * S: string
> * V: variable
> *
> - * %(E) will be expanded to "[err %d]". Likewise O, P, S, and V, will
> + * %(O) will be expanded to "[obj %d]". Likewise P, S, and V, will
> * also expand to format flags requiring an argument to the subsequent
> * sprintf or printk. T will be expanded to a string with no flags,
> * requiring no further arguments.
> @@ -401,7 +400,7 @@ static inline int is_special_flag(char *s)
> * the additional variabes, in order, to match the @fmt (except for
> * the T key), e.g.:
> *
> - * ckpt_err(ctx, "%(T)FILE flags %d %(O) %(E)\n", flags, objref, err);
> + * ckpt_err(ctx, err, "%(T)FILE flags %d %(O)\n", flags, objref);
> *
> * May be called under spinlock.
> * Must be called with ctx->msg_mutex held. The expanded format
> @@ -418,9 +417,6 @@ static void _ckpt_generate_fmt(struct ckpt_ctx *ctx, char *fmt)
> continue;
> }
> switch (fmt[2]) {
> - case 'E':
> - len += snprintf(s+len, CKPT_MSG_LEN-len, "[err %%d]");
> - break;
> case 'O':
> len += snprintf(s+len, CKPT_MSG_LEN-len, "[obj %%d]");
> break;
> @@ -455,24 +451,41 @@ static void _ckpt_generate_fmt(struct ckpt_ctx *ctx, char *fmt)
> s[len] = '\0';
> }
>
> -static void _ckpt_msg_appendv(struct ckpt_ctx *ctx, char *fmt, va_list ap)
> +static void _ckpt_msg_appendv(struct ckpt_ctx *ctx, int err, char *fmt,
> + va_list ap)
> {
> int len = ctx->msglen;
>
> + if (err) {
> + /* At restart we must use a more baroque helper to set
> + * ctx->errno, which also wakes all other waiting restarting
> + * tasks. But at checkpoint we just set ctx->errno so that
> + * _ckpt_msg_complete() will know to write the error message
> + * to the checkpoint image.
> + */
> + if (ctx->kflags & CKPT_CTX_CHECKPOINT && !ctx->errno)
> + ctx->errno = err;
> + len += snprintf(&ctx->msg[len], CKPT_MSG_LEN-len, "[err %d]",
> + err);
> + if (len > CKPT_MSG_LEN)
> + goto full;
> + }
> +
> len += vsnprintf(&ctx->msg[len], CKPT_MSG_LEN-len, fmt, ap);
> if (len > CKPT_MSG_LEN) {
> +full:
> len = CKPT_MSG_LEN;
> ctx->msg[CKPT_MSG_LEN-1] = '\0';
> }
> ctx->msglen = len;
> }
>
> -void _ckpt_msg_append(struct ckpt_ctx *ctx, char *fmt, ...)
> +void _ckpt_msg_append(struct ckpt_ctx *ctx, int err, char *fmt, ...)
> {
> va_list ap;
>
> va_start(ap, fmt);
> - _ckpt_msg_appendv(ctx, fmt, ap);
> + _ckpt_msg_appendv(ctx, err, fmt, ap);
> va_end(ap);
> }
>
> @@ -507,25 +520,25 @@ void _ckpt_msg_complete(struct ckpt_ctx *ctx)
> ctx->msglen = 0;
> }
>
> -#define __do_ckpt_msg(ctx, fmt) do { \
> - va_list ap; \
> - _ckpt_generate_fmt(ctx, fmt); \
> - va_start(ap, fmt); \
> - _ckpt_msg_appendv(ctx, ctx->fmt, ap); \
> - va_end(ap); \
> +#define __do_ckpt_msg(ctx, err, fmt) do { \
> + va_list ap; \
> + _ckpt_generate_fmt(ctx, fmt); \
> + va_start(ap, fmt); \
> + _ckpt_msg_appendv(ctx, err, ctx->fmt, ap); \
> + va_end(ap); \
> } while (0)
>
> -void _do_ckpt_msg(struct ckpt_ctx *ctx, char *fmt, ...)
> +void _do_ckpt_msg(struct ckpt_ctx *ctx, int err, char *fmt, ...)
> {
> - __do_ckpt_msg(ctx, fmt);
> + __do_ckpt_msg(ctx, err, fmt);
> }
>
> -void do_ckpt_msg(struct ckpt_ctx *ctx, char *fmt, ...)
> +void do_ckpt_msg(struct ckpt_ctx *ctx, int err, char *fmt, ...)
> {
> if (!ctx) return;
>
> ckpt_msg_lock(ctx);
> - __do_ckpt_msg(ctx, fmt);
> + __do_ckpt_msg(ctx, err, fmt);
> _ckpt_msg_complete(ctx);
> ckpt_msg_unlock(ctx);
> }
> diff --git a/include/linux/checkpoint.h b/include/linux/checkpoint.h
> index 89e6fb3..8fd6cba 100644
> --- a/include/linux/checkpoint.h
> +++ b/include/linux/checkpoint.h
> @@ -384,7 +384,7 @@ extern void ckpt_msg_unlock(struct ckpt_ctx *ctx);
> * May be called under spinlock.
> * Must be called under ckpt_msg_lock().
> */
> -extern void _ckpt_msg_append(struct ckpt_ctx *ctx, char *fmt, ...);
> +extern void _ckpt_msg_append(struct ckpt_ctx *ctx, int err, char *fmt, ...);
>
> /*
> * Write ctx->msg to all relevant places.
> @@ -399,7 +399,7 @@ extern void _ckpt_msg_complete(struct ckpt_ctx *ctx);
> * the caller will have to use _ckpt_msg_complete() to finish up.
> * Must be called with ckpt_msg_lock held.
> */
> -extern void _do_ckpt_msg(struct ckpt_ctx *ctx, char *fmt, ...);
> +extern void _do_ckpt_msg(struct ckpt_ctx *ctx, int err, char *fmt, ...);
>
> /*
> * Append an enhanced formatted message to ctx->msg.
> @@ -411,12 +411,11 @@ extern void _do_ckpt_msg(struct ckpt_ctx *ctx, char *fmt, ...);
> *
> * Must not be called under spinlock.
> */
> -extern void do_ckpt_msg(struct ckpt_ctx *ctx, char *fmt, ...);
> +extern void do_ckpt_msg(struct ckpt_ctx *ctx, int err, char *fmt, ...);
>
> #define ckpt_err(ctx, err, fmt, args...) do { \
> - ctx->errno = (err); \
> - do_ckpt_msg(ctx, "[Error at %s:%d][err %d]" fmt, __func__, __LINE__, \
> - (err), ##args); \
> + do_ckpt_msg(ctx, (err), "[Error at %s:%d]" fmt, __func__, __LINE__, \
> + ##args); \
> } while (0)
>
>
> @@ -427,9 +426,8 @@ extern void do_ckpt_msg(struct ckpt_ctx *ctx, char *fmt, ...);
> * must be followed by a call to _ckpt_msg_complete()
> */
> #define _ckpt_err(ctx, err, fmt, args...) do { \
> - ctx->errno = (err); \
> - _do_ckpt_msg(ctx, "[ error %s:%d][err %d]" fmt, __func__, __LINE__, \
> - (err), ##args); \
> + _do_ckpt_msg(ctx, (err), "[Error at %s:%d]" fmt, __func__, __LINE__, \
> + ##args); \
> } while (0)
>
> #endif /* CONFIG_CHECKPOINT */
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