Date: Tue, 14 May 2019 20:41:24 +0000 (UTC) From: Edward Tomasz Napierala <trasz@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-stable@freebsd.org, svn-src-stable-12@freebsd.org Subject: svn commit: r347579 - stable/12/sys/kern Message-ID: <201905142041.x4EKfO7v078703@repo.freebsd.org>
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Author: trasz Date: Tue May 14 20:41:24 2019 New Revision: 347579 URL: https://svnweb.freebsd.org/changeset/base/347579 Log: MFC r346120: Use shared vnode locks for the ELF interpreter. Sponsored by: DARPA, AFRL Modified: stable/12/sys/kern/imgact_elf.c Directory Properties: stable/12/ (props changed) Modified: stable/12/sys/kern/imgact_elf.c ============================================================================== --- stable/12/sys/kern/imgact_elf.c Tue May 14 20:32:29 2019 (r347578) +++ stable/12/sys/kern/imgact_elf.c Tue May 14 20:41:24 2019 (r347579) @@ -717,7 +717,7 @@ __elfN(load_file)(struct proc *p, const char *file, u_ struct nameidata *nd; struct vattr *attr; struct image_params *imgp; - u_long rbase; + u_long flags, rbase; u_long base_addr = 0; int error; @@ -745,7 +745,10 @@ __elfN(load_file)(struct proc *p, const char *file, u_ imgp->object = NULL; imgp->execlabel = NULL; - NDINIT(nd, LOOKUP, LOCKLEAF | FOLLOW, UIO_SYSSPACE, file, curthread); + flags = FOLLOW | LOCKSHARED | LOCKLEAF; + +again: + NDINIT(nd, LOOKUP, flags, UIO_SYSSPACE, file, curthread); if ((error = namei(nd)) != 0) { nd->ni_vp = NULL; goto fail; @@ -760,15 +763,30 @@ __elfN(load_file)(struct proc *p, const char *file, u_ if (error) goto fail; + /* + * Also make certain that the interpreter stays the same, + * so set its VV_TEXT flag, too. Since this function is only + * used to load the interpreter, the VV_TEXT is almost always + * already set. + */ + if (VOP_IS_TEXT(nd->ni_vp) == 0) { + if (VOP_ISLOCKED(nd->ni_vp) != LK_EXCLUSIVE) { + /* + * LK_UPGRADE could have resulted in dropping + * the lock. Just try again from the start, + * this time with exclusive vnode lock. + */ + vput(nd->ni_vp); + flags &= ~LOCKSHARED; + goto again; + } + + VOP_SET_TEXT(nd->ni_vp); + } + error = exec_map_first_page(imgp); if (error) goto fail; - - /* - * Also make certain that the interpreter stays the same, so set - * its VV_TEXT flag, too. - */ - VOP_SET_TEXT(nd->ni_vp); imgp->object = nd->ni_vp->v_object;
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