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- Use fd_lastfile + 1 as the upper bound on nd. This is more correct than

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using the size of the descriptor array.
 - A lock is not needed to fetch fd_lastfile.  The results are stale the
   instant it is dropped.
 - Use a private mutex pool for select since the pool mutex is not used
   as a leaf.
 - Fetch the si_mtx pointer first before resorting to hashing to compute
   the mutex address.

Reviewed by:	McKusick
Approved by:	re (kib)
This commit is contained in:
Jeff Roberson 2009-07-01 20:43:46 +00:00
parent 8edfe76ab5
commit 2141453eb4
1 changed files with 8 additions and 6 deletions
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14
sys/kern/sys_generic.c
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@ -124,6 +124,7 @@ struct selfd {
};
static uma_zone_t selfd_zone;
static struct mtx_pool *mtxpool_select;
#ifndef _SYS_SYSPROTO_H_
struct read_args {
@ -794,11 +795,8 @@ kern_select(struct thread *td, int nd, fd_set *fd_in, fd_set *fd_ou,
if (nd < 0)
return (EINVAL);
fdp = td->td_proc->p_fd;
FILEDESC_SLOCK(fdp);
if (nd > td->td_proc->p_fd->fd_nfiles)
nd = td->td_proc->p_fd->fd_nfiles; /* forgiving; slightly wrong */
FILEDESC_SUNLOCK(fdp);
if (nd > fdp->fd_lastfile + 1)
nd = fdp->fd_lastfile + 1;
/*
* Allocate just enough bits for the non-null fd_sets. Use the
@ -1373,7 +1371,9 @@ selrecord(selector, sip)
stp->st_free2 = NULL;
else
panic("selrecord: No free selfd on selq");
mtxp = mtx_pool_find(mtxpool_sleep, sip);
mtxp = sip->si_mtx;
if (mtxp == NULL)
mtxp = mtx_pool_find(mtxpool_select, sip);
/*
* Initialize the sfp and queue it in the thread.
*/
@ -1529,6 +1529,8 @@ SYSINIT(select, SI_SUB_SYSCALLS, SI_ORDER_ANY, selectinit, NULL);
static void
selectinit(void *dummy __unused)
{
selfd_zone = uma_zcreate("selfd", sizeof(struct selfd), NULL, NULL,
NULL, NULL, UMA_ALIGN_PTR, 0);
mtxpool_select = mtx_pool_create("select mtxpool", 128, MTX_DEF);
}