Author: mjg Date: Sat Jul 11 21:57:03 2020 New Revision: 363112 URL: https://svnweb.freebsd.org/changeset/base/363112
Log: fd: stop looping in pwd_hold We don't expect to fail acquiring the reference unless running into a corner case. Just in case ensure forward progress by taking the lock. Reviewed by: kib, markj Differential Revision: https://reviews.freebsd.org/D25616 Modified: head/sys/kern/kern_descrip.c Modified: head/sys/kern/kern_descrip.c ============================================================================== --- head/sys/kern/kern_descrip.c Sat Jul 11 20:56:57 2020 (r363111) +++ head/sys/kern/kern_descrip.c Sat Jul 11 21:57:03 2020 (r363112) @@ -3347,13 +3347,17 @@ pwd_hold(struct thread *td) fdp = td->td_proc->p_fd; smr_enter(pwd_smr); - for (;;) { - pwd = smr_entered_load(&fdp->fd_pwd, pwd_smr); - MPASS(pwd != NULL); - if (refcount_acquire_if_not_zero(&pwd->pwd_refcount)) - break; + pwd = smr_entered_load(&fdp->fd_pwd, pwd_smr); + MPASS(pwd != NULL); + if (__predict_true(refcount_acquire_if_not_zero(&pwd->pwd_refcount))) { + smr_exit(pwd_smr); + return (pwd); } smr_exit(pwd_smr); + FILEDESC_SLOCK(fdp); + pwd = pwd_hold_filedesc(fdp); + MPASS(pwd != NULL); + FILEDESC_SUNLOCK(fdp); return (pwd); } _______________________________________________ svn-src-all@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/svn-src-all To unsubscribe, send any mail to "svn-src-all-unsubscr...@freebsd.org"
