mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-09-13 22:25:03 +00:00
0563231f93
There's several places that open code the following logic:
TP_STRUCT__entry(__dynamic_array(char, msg, MSG_MAX)),
TP_fast_assign(vsnprintf(__get_str(msg), MSG_MAX, vaf->fmt, *vaf->va);)
To load a string created by variable array va_list.
The main issue with this approach is that "MSG_MAX" usage in the
__dynamic_array() portion. That actually just reserves the MSG_MAX in the
event, and even wastes space because there's dynamic meta data also saved
in the event to denote the offset and size of the dynamic array. It would
have been better to just use a static __array() field.
Instead, create __vstring() and __assign_vstr() that work like __string
and __assign_str() but instead of taking a destination string to copy,
take a format string and a va_list pointer and fill in the values.
It uses the helper:
#define __trace_event_vstr_len(fmt, va) \
({ \
va_list __ap; \
int __ret; \
\
va_copy(__ap, *(va)); \
__ret = vsnprintf(NULL, 0, fmt, __ap) + 1; \
va_end(__ap); \
\
min(__ret, TRACE_EVENT_STR_MAX); \
})
To figure out the length to store the string. It may be slightly slower as
it needs to run the vsnprintf() twice, but it now saves space on the ring
buffer.
Link: https://lkml.kernel.org/r/20220705224749.053570613@goodmis.org
Cc: Dennis Dalessandro <dennis.dalessandro@cornelisnetworks.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Leon Romanovsky <leon@kernel.org>
Cc: Kalle Valo <kvalo@kernel.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Paolo Abeni <pabeni@redhat.com>
Cc: Arend van Spriel <aspriel@gmail.com>
Cc: Franky Lin <franky.lin@broadcom.com>
Cc: Hante Meuleman <hante.meuleman@broadcom.com>
Cc: Gregory Greenman <gregory.greenman@intel.com>
Cc: Peter Chen <peter.chen@kernel.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Mathias Nyman <mathias.nyman@intel.com>
Cc: Chunfeng Yun <chunfeng.yun@mediatek.com>
Cc: Bin Liu <b-liu@ti.com>
Cc: Marek Lindner <mareklindner@neomailbox.ch>
Cc: Simon Wunderlich <sw@simonwunderlich.de>
Cc: Antonio Quartulli <a@unstable.cc>
Cc: Sven Eckelmann <sven@narfation.org>
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: Jim Cromie <jim.cromie@gmail.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
93 lines
2.8 KiB
C
93 lines
2.8 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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/* Stage 5 definitions for creating trace events */
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/*
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* remember the offset of each array from the beginning of the event.
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*/
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#undef __entry
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#define __entry entry
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#undef __field
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#define __field(type, item)
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#undef __field_ext
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#define __field_ext(type, item, filter_type)
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#undef __field_struct
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#define __field_struct(type, item)
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#undef __field_struct_ext
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#define __field_struct_ext(type, item, filter_type)
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#undef __array
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#define __array(type, item, len)
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#undef __dynamic_array
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#define __dynamic_array(type, item, len) \
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__item_length = (len) * sizeof(type); \
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__data_offsets->item = __data_size + \
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offsetof(typeof(*entry), __data); \
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__data_offsets->item |= __item_length << 16; \
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__data_size += __item_length;
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#undef __string
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#define __string(item, src) __dynamic_array(char, item, \
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strlen((src) ? (const char *)(src) : "(null)") + 1)
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#undef __string_len
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#define __string_len(item, src, len) __dynamic_array(char, item, (len) + 1)
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#undef __vstring
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#define __vstring(item, fmt, ap) __dynamic_array(char, item, \
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__trace_event_vstr_len(fmt, ap))
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#undef __rel_dynamic_array
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#define __rel_dynamic_array(type, item, len) \
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__item_length = (len) * sizeof(type); \
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__data_offsets->item = __data_size + \
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offsetof(typeof(*entry), __data) - \
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offsetof(typeof(*entry), __rel_loc_##item) - \
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sizeof(u32); \
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__data_offsets->item |= __item_length << 16; \
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__data_size += __item_length;
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#undef __rel_string
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#define __rel_string(item, src) __rel_dynamic_array(char, item, \
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strlen((src) ? (const char *)(src) : "(null)") + 1)
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#undef __rel_string_len
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#define __rel_string_len(item, src, len) __rel_dynamic_array(char, item, (len) + 1)
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/*
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* __bitmask_size_in_bytes_raw is the number of bytes needed to hold
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* num_possible_cpus().
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*/
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#define __bitmask_size_in_bytes_raw(nr_bits) \
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(((nr_bits) + 7) / 8)
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#define __bitmask_size_in_longs(nr_bits) \
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((__bitmask_size_in_bytes_raw(nr_bits) + \
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((BITS_PER_LONG / 8) - 1)) / (BITS_PER_LONG / 8))
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/*
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* __bitmask_size_in_bytes is the number of bytes needed to hold
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* num_possible_cpus() padded out to the nearest long. This is what
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* is saved in the buffer, just to be consistent.
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*/
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#define __bitmask_size_in_bytes(nr_bits) \
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(__bitmask_size_in_longs(nr_bits) * (BITS_PER_LONG / 8))
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#undef __bitmask
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#define __bitmask(item, nr_bits) __dynamic_array(unsigned long, item, \
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__bitmask_size_in_longs(nr_bits))
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#undef __rel_bitmask
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#define __rel_bitmask(item, nr_bits) __rel_dynamic_array(unsigned long, item, \
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__bitmask_size_in_longs(nr_bits))
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#undef __sockaddr
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#define __sockaddr(field, len) __dynamic_array(u8, field, len)
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#undef __rel_sockaddr
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#define __rel_sockaddr(field, len) __rel_dynamic_array(u8, field, len)
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