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Commit 2c470475 authored by Eric W. Biederman's avatar Eric W. Biederman
Browse files

pids: Move the pgrp and session pid pointers from task_struct to signal_struct 



To access these fields the code always has to go to group leader so
going to signal struct is no loss and is actually a fundamental simplification.

This saves a little bit of memory by only allocating the pid pointer array
once instead of once for every thread, and even better this removes a
few potential races caused by the fact that group_leader can be changed
by de_thread, while signal_struct can not.

Signed-off-by: default avatar"Eric W. Biederman" <ebiederm@xmission.com>
parent 71dbc8a9

arch/ia64/kernel/asm-offsets.c

+1 −1
Original line number Diff line number Diff line
@@ -50,7 +50,7 @@ void foo(void) 


	DEFINE(IA64_TASK_BLOCKED_OFFSET,offsetof (struct task_struct, blocked));

	DEFINE(IA64_TASK_CLEAR_CHILD_TID_OFFSET,offsetof (struct task_struct, clear_child_tid));

	DEFINE(IA64_TASK_TGIDLINK_OFFSET, offsetof (struct task_struct, pids[PIDTYPE_PID].pid));

	DEFINE(IA64_TASK_THREAD_PID_OFFSET,offsetof (struct task_struct, thread_pid));

	DEFINE(IA64_PID_LEVEL_OFFSET, offsetof (struct pid, level));

	DEFINE(IA64_PID_UPID_OFFSET, offsetof (struct pid, numbers[0]));

	DEFINE(IA64_TASK_PENDING_OFFSET,offsetof (struct task_struct, pending));

arch/ia64/kernel/fsys.S

+2 −2
Original line number Diff line number Diff line
@@ -96,11 +96,11 @@ ENTRY(fsys_set_tid_address) 
	.altrp b6

	.body

	add r9=TI_FLAGS+IA64_TASK_SIZE,r16

	add r17=IA64_TASK_TGIDLINK_OFFSET,r16

	add r17=IA64_TASK_THREAD_PID_OFFSET,r16

	;;

	ld4 r9=[r9]

	tnat.z p6,p7=r32		// check argument register for being NaT

	ld8 r17=[r17]				// r17 = current->pids[PIDTYPE_PID].pid

	ld8 r17=[r17]				// r17 = current->thread_pid

	;;

	and r9=TIF_ALLWORK_MASK,r9

	add r8=IA64_PID_LEVEL_OFFSET,r17

fs/autofs/autofs_i.h

+1 −0
Original line number Diff line number Diff line
@@ -18,6 +18,7 @@ 
#include <linux/string.h>

#include <linux/wait.h>

#include <linux/sched.h>

#include <linux/sched/signal.h>

#include <linux/mount.h>

#include <linux/namei.h>

#include <linux/uaccess.h>

include/linux/init_task.h

+0 −9
Original line number Diff line number Diff line
@@ -46,15 +46,6 @@ extern struct cred init_cred; 
#define INIT_CPU_TIMERS(s)

#endif



#define INIT_PID_LINK(type) 					\

{								\

	.node = {						\

		.next = NULL,					\

		.pprev = NULL,					\

	},							\

	.pid = &init_struct_pid,				\

}



#define INIT_TASK_COMM "swapper"



/* Attach to the init_task data structure for proper alignment */

include/linux/pid.h

+1 −7
Original line number Diff line number Diff line
@@ -67,12 +67,6 @@ struct pid 


extern struct pid init_struct_pid;



struct pid_link

{

	struct hlist_node node;

	struct pid *pid;

};



static inline struct pid *get_pid(struct pid *pid)

{

	if (pid)
@@ -177,7 +171,7 @@ pid_t pid_vnr(struct pid *pid); 
	do {								\

		if ((pid) != NULL)					\

			hlist_for_each_entry_rcu((task),		\

				&(pid)->tasks[type], pids[type].node) {

				&(pid)->tasks[type], pid_links[type]) {



			/*

			 * Both old and new leaders may be attached to