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Add a way to distinguish between forking and thread creation in schedtail.

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For CloudABI we need to initialize the registers of new threads
differently based on whether the thread got created through a fork or
through simple thread creation.

Add a flag, TDP_FORKING, that is set by do_fork() and cleared by
fork_exit(). This can be tested against in schedtail.

Reviewed by:	kib
Differential Revision:	https://reviews.freebsd.org/D3973
This commit is contained in:
ed 2015-10-22 09:33:34 +00:00
parent 7fb0afec66
commit 8be8acd7af
3 changed files with 6 additions and 2 deletions
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3
sys/kern/kern_fork.c
View File

@ -586,7 +586,7 @@ do_fork(struct thread *td, int flags, struct proc *p2, struct thread *td2,
* been preserved.
*/
p2->p_flag |= p1->p_flag & P_SUGID;
td2->td_pflags |= td->td_pflags & TDP_ALTSTACK;
td2->td_pflags |= (td->td_pflags & TDP_ALTSTACK) | TDP_FORKING;
SESS_LOCK(p1->p_session);
if (p1->p_session->s_ttyvp != NULL && p1->p_flag & P_CONTROLT)
p2->p_flag |= P_CONTROLT;
@ -1023,6 +1023,7 @@ fork_exit(void (*callout)(void *, struct trapframe *), void *arg,
if (p->p_sysent->sv_schedtail != NULL)
(p->p_sysent->sv_schedtail)(td);
td->td_pflags &= ~TDP_FORKING;
}
/*

3
sys/kern/subr_syscall.c
View File

@ -176,6 +176,9 @@ syscallret(struct thread *td, int error, struct syscall_args *sa)
struct proc *p, *p2;
int traced;
KASSERT((td->td_pflags & TDP_FORKING) == 0,
("fork() did not clear TDP_FORKING upon completion"));
p = td->td_proc;
/*

2
sys/sys/proc.h
View File

@ -446,7 +446,7 @@ do { \
#define TDP_RESETSPUR 0x04000000 /* Reset spurious page fault history. */
#define TDP_NERRNO 0x08000000 /* Last errno is already in td_errno */
#define TDP_UIOHELD 0x10000000 /* Current uio has pages held in td_ma */
#define TDP_UNUSED29 0x20000000 /* --available-- */
#define TDP_FORKING 0x20000000 /* Thread is being created through fork() */
#define TDP_EXECVMSPC 0x40000000 /* Execve destroyed old vmspace */
/*