binutils-gdb/gdb/gdbserver/inferiors.h
Yao Qi 8934261877 Get pending events in random
Nowadays, we select events to be reported to GDB in random, however
that is not enough when many GDBserver internal events (not reported
to GDB) are generated.

GDBserver pulls all events out of kernel via waitpid, and leave them
pending.  When goes through threads which have pending events,
GDBserver uses find_inferior to find the first thread which has
pending event, and consumes it.  Note that find_inferior always
iterate threads in a fixed order.  If multiple threads keep hitting
GDBserver breakpoints, range stepping with single-step breakpoint for
example, threads in the head of the thread list are more likely to be
processed and threads in the tail are starved.  This causes some timeout
fails in gdb.threads/non-stop-fair-events.exp when range stepping is
enabled on arm-linux.

This patch fixes this issue by randomly selecting pending events.  It
adds a new function find_inferior_in_random, which iterates threads
which have pending events randomly.

gdb/gdbserver:

2016-10-27  Yao Qi  <yao.qi@linaro.org>

	* inferiors.c (find_inferior_in_random): New function.
	* inferiors.h (find_inferior_in_random): Declare.
	* linux-low.c (linux_wait_for_event_filtered): Call
	find_inferior_in_random instead of find_inferior.
2016-10-27 16:05:06 +01:00

168 lines
5.3 KiB
C

/* Inferior process information for the remote server for GDB.
Copyright (C) 1993-2016 Free Software Foundation, Inc.
This file is part of GDB.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>. */
#ifndef INFERIORS_H
#define INFERIORS_H
#include "gdb_vecs.h"
/* Generic information for tracking a list of ``inferiors'' - threads,
processes, etc. */
struct inferior_list
{
struct inferior_list_entry *head;
struct inferior_list_entry *tail;
};
struct inferior_list_entry
{
ptid_t id;
struct inferior_list_entry *next;
};
struct thread_info;
struct regcache;
struct target_desc;
struct sym_cache;
struct breakpoint;
struct raw_breakpoint;
struct fast_tracepoint_jump;
struct process_info_private;
struct process_info
{
/* This must appear first.
The list iterator functions assume it. */
struct inferior_list_entry entry;
/* Nonzero if this child process was attached rather than
spawned. */
int attached;
/* True if GDB asked us to detach from this process, but we remained
attached anyway. */
int gdb_detached;
/* The symbol cache. */
struct sym_cache *symbol_cache;
/* The list of memory breakpoints. */
struct breakpoint *breakpoints;
/* The list of raw memory breakpoints. */
struct raw_breakpoint *raw_breakpoints;
/* The list of installed fast tracepoints. */
struct fast_tracepoint_jump *fast_tracepoint_jumps;
/* The list of syscalls to report, or just a single element, ANY_SYSCALL,
for unfiltered syscall reporting. */
VEC (int) *syscalls_to_catch;
const struct target_desc *tdesc;
/* Private target data. */
struct process_info_private *priv;
};
#define ptid_of(inf) ((inf)->entry.id)
#define pid_of(inf) ptid_get_pid ((inf)->entry.id)
#define lwpid_of(inf) ptid_get_lwp ((inf)->entry.id)
/* Return a pointer to the process that corresponds to the current
thread (current_thread). It is an error to call this if there is
no current thread selected. */
struct process_info *current_process (void);
struct process_info *get_thread_process (const struct thread_info *);
extern struct inferior_list all_processes;
void add_inferior_to_list (struct inferior_list *list,
struct inferior_list_entry *new_inferior);
void for_each_inferior (struct inferior_list *list,
void (*action) (struct inferior_list_entry *));
void for_each_inferior_with_data
(struct inferior_list *list,
void (*action) (struct inferior_list_entry *, void *),
void *data);
void clear_inferior_list (struct inferior_list *list);
int one_inferior_p (struct inferior_list *list);
/* Helper for ALL_INFERIORS_TYPE. Gets the next element starting at
CUR, if CUR is not NULL. */
#define A_I_NEXT(type, list, cur) \
((cur) != NULL \
? (type *) ((struct inferior_list_entry *) cur)->next \
: NULL)
/* Iterate over all inferiors of type TYPE in LIST, open loop
style. */
#define ALL_INFERIORS_TYPE(type, list, cur, tmp) \
for ((cur) = (type *) (list)->head, (tmp) = A_I_NEXT (type, list, cur); \
(cur) != NULL; \
(cur) = (tmp), (tmp) = A_I_NEXT (type, list, cur))
/* Iterate over all inferiors in LIST, open loop style. */
#define ALL_INFERIORS(list, cur, tmp) \
ALL_INFERIORS_TYPE (struct inferior_list_entry, list, cur, tmp)
/* Iterate over all processes, open loop style. */
#define ALL_PROCESSES(cur, tmp) \
ALL_INFERIORS_TYPE (struct process_info, &all_processes, cur, tmp)
extern struct thread_info *current_thread;
void remove_inferior (struct inferior_list *list,
struct inferior_list_entry *entry);
struct inferior_list_entry *get_first_inferior (struct inferior_list *list);
/* Return the first process in the processes list. */
struct process_info *get_first_process (void);
struct process_info *add_process (int pid, int attached);
void remove_process (struct process_info *process);
struct process_info *find_process_pid (int pid);
int have_started_inferiors_p (void);
int have_attached_inferiors_p (void);
ptid_t thread_to_gdb_id (struct thread_info *);
ptid_t gdb_id_to_thread_id (ptid_t);
void clear_inferiors (void);
struct inferior_list_entry *find_inferior
(struct inferior_list *,
int (*func) (struct inferior_list_entry *,
void *),
void *arg);
struct inferior_list_entry *find_inferior_id (struct inferior_list *list,
ptid_t id);
struct inferior_list_entry *
find_inferior_in_random (struct inferior_list *,
int (*func) (struct inferior_list_entry *,
void *),
void *arg);
void *inferior_target_data (struct thread_info *);
void set_inferior_target_data (struct thread_info *, void *);
struct regcache *inferior_regcache_data (struct thread_info *);
void set_inferior_regcache_data (struct thread_info *, struct regcache *);
#endif /* INFERIORS_H */