[RFC 2/4] Add eventfd option to --decode-fds

[Dmitry V. Levin]

Hi,

On Mon, Apr 29, 2024 at 09:01:45AM +0530, Sahil Siddiq wrote:
> Having an eventfd option for --decode-fds will help
> examine the eventfd counter associated with an eventfd
> file descriptor.
> 
> * src/filter_qualify.c
>   (decode_fd_str_to_uint): Add "eventfd" option.
>   (parse_inject_token): Pass base 10 as argument.
> * src/number_set.h: Add DECODE_FD_EVENTFD.
> * src/strace.c: Add "eventfd" option.
> * src/util.c: Parse eventfd counter value.
> 
> Signed-off-by: Sahil Siddiq <icegambit91 at gmail.com>
> ---
>  src/filter_qualify.c |  5 +++--
>  src/number_set.h     |  1 +
>  src/strace.c         |  3 ++-
>  src/util.c           | 37 +++++++++++++++++++++++++++++++++++++
>  4 files changed, 43 insertions(+), 3 deletions(-)
> 
> diff --git a/src/filter_qualify.c b/src/filter_qualify.c
> index be383a5c9..a79045468 100644
> --- a/src/filter_qualify.c
> +++ b/src/filter_qualify.c
> @@ -105,6 +105,7 @@ decode_fd_str_to_uint(const char *str)
>  		{ DECODE_FD_PATH,      "path" },
>  		{ DECODE_FD_SOCKET,    "socket" },
>  		{ DECODE_FD_DEV,       "dev" },
> +		{ DECODE_FD_EVENTFD,   "eventfd" },
>  		{ DECODE_FD_PIDFD,     "pidfd" },
>  		{ DECODE_FD_SIGNALFD,  "signalfd" },
>  	};
> @@ -273,7 +274,7 @@ parse_inject_token(const char *const token, struct inject_opts *const fopts,
>  		 * F..L+S
>  		 */
>  		char *end;
> -		intval = string_to_uint_ex(val, &end, 0xffff, "+.");
> +		intval = string_to_uint_ex(val, &end, 0xffff, "+.", 10);
>  		if (intval < 1)
>  			return false;
>  
> @@ -287,7 +288,7 @@ parse_inject_token(const char *const token, struct inject_opts *const fopts,
>  			 * F..L+S
>  			 */
>  			val = end + 2;
> -			intval = string_to_uint_ex(val, &end, 0xffff, "+");
> +			intval = string_to_uint_ex(val, &end, 0xffff, "+", 10);
>  			if (intval < fopts->first || intval == INJECT_LAST_INF)
>  				return false;
>  			fopts->last = intval;

Looks like this two hunks belong to the previous patch in the series.

> diff --git a/src/number_set.h b/src/number_set.h
> index 0ce2b2db6..d28ac0cdd 100644
> --- a/src/number_set.h
> +++ b/src/number_set.h
> @@ -75,6 +75,7 @@ enum decode_fd_bits {
>  	DECODE_FD_PATH,
>  	DECODE_FD_SOCKET,
>  	DECODE_FD_DEV,
> +	DECODE_FD_EVENTFD,
>  	DECODE_FD_PIDFD,
>  	DECODE_FD_SIGNALFD,
>  
> diff --git a/src/strace.c b/src/strace.c
> index c8f76cada..a5f87c3bb 100644
> --- a/src/strace.c
> +++ b/src/strace.c
> @@ -378,7 +378,8 @@ Output format:\n\
>                   print exit reason of kvm vcpu\n\
>    -e decode-fds=SET, --decode-fds=SET\n\
>                   what kinds of file descriptor information details to decode\n\
> -     details:    dev (device major/minor for block/char device files)\n\
> +     details:    dev (device major/minor for block/char device files),\n\
> +                 eventfd (associated eventfd counter for eventfds),\n\
>                   path (file path),\n\
>                   pidfd (associated PID for pidfds),\n\
>                   socket (protocol-specific information for socket descriptors),\n\
> diff --git a/src/util.c b/src/util.c
> index 4140cb718..edcdf440c 100644
> --- a/src/util.c
> +++ b/src/util.c
> @@ -858,6 +858,40 @@ printsignalfd(pid_t pid_of_fd, int fd, const char *path)
>  			   print_fdinfo_sigmask, NULL);
>  }
>  
> +static bool
> +parse_fdinfo_efd_counter(const char *value, void *data)
> +{	uint64_t *efd_counter = data;
> +	*efd_counter = string_to_uint_ex(value, NULL, ULLONG_MAX, "\n", 16);
> +	return true;
> +}
> +
> +static bool
> +printeventfd(pid_t pid_of_fd, int fd, const char *path)
> +{
> +	static const char eventfd_path[] = "anon_inode:[eventfd]";
> +	static const char efd_counter_pfx[] = "eventfd-count:";
> +
> +	if (strcmp(path, eventfd_path))
> +		return false;
> +
> +	uint64_t efd_counter = -1ULL;
> +
> +	scan_fdinfo(pid_of_fd, fd, efd_counter_pfx, sizeof(efd_counter_pfx) - 1,
> +			   parse_fdinfo_efd_counter, &efd_counter);
> +
> +	if (efd_counter != -1ULL) {
> +		tprint_associated_info_begin();
> +		tprints_string("eventfd-count:");
> +		PRINT_VAL_U(efd_counter);
> +		tprint_associated_info_end();
> +	} else {
> +		;
> +		// print_string_in_angle_brackets(path);
> +	}

What is this "else" branch for?
Anyway, we don't use // comments.


-- 
ldv