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Don't generate data in sysctl_out_proc unless we intend to copy out.

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The first call is used to gauge how much spaces is needed. Just computing
the size instead of generating the output allows to not take the proctree
lock.
This commit is contained in:
Mateusz Guzik 2018-02-25 15:16:58 +00:00
parent 7d3761dc72
commit 9d4e369ae8
1 changed files with 46 additions and 12 deletions
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58
sys/kern/kern_proc.c
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@ -1347,6 +1347,32 @@ freebsd32_kinfo_proc_out(const struct kinfo_proc *ki, struct kinfo_proc32 *ki32)
}
#endif
static ssize_t
kern_proc_out_size(struct proc *p, int flags)
{
ssize_t size = 0;
PROC_LOCK_ASSERT(p, MA_OWNED);
if ((flags & KERN_PROC_NOTHREADS) != 0) {
#ifdef COMPAT_FREEBSD32
if ((flags & KERN_PROC_MASK32) != 0) {
size += sizeof(struct kinfo_proc32);
} else
#endif
size += sizeof(struct kinfo_proc);
} else {
#ifdef COMPAT_FREEBSD32
if ((flags & KERN_PROC_MASK32) != 0)
size += sizeof(struct kinfo_proc32) * p->p_numthreads;
else
#endif
size += sizeof(struct kinfo_proc) * p->p_numthreads;
}
PROC_UNLOCK(p);
return (size);
}
int
kern_proc_out(struct proc *p, struct sbuf *sb, int flags)
{
@ -1399,6 +1425,9 @@ sysctl_out_proc(struct proc *p, struct sysctl_req *req, int flags)
struct kinfo_proc ki;
int error, error2;
if (req->oldptr == NULL)
return (SYSCTL_OUT(req, 0, kern_proc_out_size(p, flags)));
sbuf_new_for_sysctl(&sb, (char *)&ki, sizeof(ki), req);
sbuf_clear_flags(&sb, SBUF_INCLUDENUL);
error = kern_proc_out(p, &sb, flags);
@ -1461,16 +1490,22 @@ sysctl_kern_proc(SYSCTL_HANDLER_ARGS)
break;
}
if (!req->oldptr) {
if (req->oldptr == NULL) {
/* overestimate by 5 procs */
error = SYSCTL_OUT(req, 0, sizeof (struct kinfo_proc) * 5);
if (error)
return (error);
} else {
error = sysctl_wire_old_buffer(req, 0);
if (error != 0)
return (error);
/*
* This lock is only needed to safely grab the parent of a
* traced process. Only grab it if we are producing any
* data to begin with.
*/
sx_slock(&proctree_lock);
}
error = sysctl_wire_old_buffer(req, 0);
if (error != 0)
return (error);
sx_slock(&proctree_lock);
sx_slock(&allproc_lock);
for (doingzomb=0 ; doingzomb < 2 ; doingzomb++) {
if (!doingzomb)
@ -1571,16 +1606,15 @@ sysctl_kern_proc(SYSCTL_HANDLER_ARGS)
}
error = sysctl_out_proc(p, req, flags);
if (error) {
sx_sunlock(&allproc_lock);
sx_sunlock(&proctree_lock);
return (error);
}
if (error)
goto out;
}
}
out:
sx_sunlock(&allproc_lock);
sx_sunlock(&proctree_lock);
return (0);
if (req->oldptr != NULL)
sx_sunlock(&proctree_lock);
return (error);
}
struct pargs *