Author: mjg
Date: Thu Dec 17 18:52:30 2020
New Revision: 368732
URL: https://svnweb.freebsd.org/changeset/base/368732
Log:
fd: reimplement close_range to avoid spurious relocking
Modified:
head/sys/kern/kern_descrip.c
Modified: head/sys/kern/kern_descrip.c
==============================================================================
--- head/sys/kern/kern_descrip.c Thu Dec 17 18:52:04 2020
(r368731)
+++ head/sys/kern/kern_descrip.c Thu Dec 17 18:52:30 2020
(r368732)
@@ -307,6 +307,7 @@ fdfree(struct filedesc *fdp, int fd)
{
struct filedescent *fde;
+ FILEDESC_XLOCK_ASSERT(fdp);
fde = &fdp->fd_ofiles[fd];
#ifdef CAPABILITIES
seqc_write_begin(&fde->fde_seqc);
@@ -1367,12 +1368,10 @@ int
kern_close_range(struct thread *td, u_int lowfd, u_int highfd)
{
struct filedesc *fdp;
- int fd, ret, lastfile;
+ const struct fdescenttbl *fdt;
+ struct file *fp;
+ int fd;
- ret = 0;
- fdp = td->td_proc->p_fd;
- FILEDESC_SLOCK(fdp);
-
/*
* Check this prior to clamping; closefrom(3) with only fd 0, 1, and 2
* open should not be a usage error. From a close_range() perspective,
@@ -1380,30 +1379,36 @@ kern_close_range(struct thread *td, u_int lowfd, u_int
* be a usage error as all fd above 3 are in-fact already closed.
*/
if (highfd < lowfd) {
- ret = EINVAL;
- goto out;
+ return (EINVAL);
}
- /*
- * If lastfile == -1, we're dealing with either a fresh file
- * table or one in which every fd has been closed. Just return
- * successful; there's nothing left to do.
- */
- lastfile = fdlastfile(fdp);
- if (lastfile == -1)
- goto out;
- /* Clamped to [lowfd, lastfile] */
- highfd = MIN(highfd, lastfile);
- for (fd = lowfd; fd <= highfd; fd++) {
- if (fdp->fd_ofiles[fd].fde_file != NULL) {
- FILEDESC_SUNLOCK(fdp);
- (void)kern_close(td, fd);
- FILEDESC_SLOCK(fdp);
+ fdp = td->td_proc->p_fd;
+ FILEDESC_XLOCK(fdp);
+ fdt = atomic_load_ptr(&fdp->fd_files);
+ highfd = MIN(highfd, fdt->fdt_nfiles - 1);
+ fd = lowfd;
+ if (__predict_false(fd > highfd)) {
+ goto out_locked;
+ }
+ for (;;) {
+ fp = fdt->fdt_ofiles[fd].fde_file;
+ if (fp == NULL) {
+ if (fd == highfd)
+ goto out_locked;
+ } else {
+ fdfree(fdp, fd);
+ (void) closefp(fdp, fd, fp, td, true, true);
+ if (fd == highfd)
+ goto out_unlocked;
+ FILEDESC_XLOCK(fdp);
+ fdt = atomic_load_ptr(&fdp->fd_files);
}
+ fd++;
}
-out:
- FILEDESC_SUNLOCK(fdp);
- return (ret);
+out_locked:
+ FILEDESC_XUNLOCK(fdp);
+out_unlocked:
+ return (0);
}
#ifndef _SYS_SYSPROTO_H_
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