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Further refine the handling of stop signals in the NFS client. The

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changes in r246417 were incomplete as they did not add explicit calls to
sigdeferstop() around all the places that previously passed SBDRY to
_sleep().  In addition, nfs_getcacheblk() could trigger a write RPC from
getblk() resulting in sigdeferstop() recursing.  Rather than manually
deferring stop signals in specific places, change the VFS_*() and VOP_*()
methods to defer stop signals for filesystems which request this behavior
via a new VFCF_SBDRY flag.  Note that this has to be a VFC flag rather than
a MNTK flag so that it works properly with VFS_MOUNT() when the mount is
not yet fully constructed.  For now, only the NFS clients are set this new
flag in VFS_SET().

A few other related changes:
- Add an assertion to ensure that TDF_SBDRY doesn't leak to userland.
- When a lookup request uses VOP_READLINK() to follow a symlink, mark
  the request as being on behalf of the thread performing the lookup
  (cnp_thread) rather than using a NULL thread pointer.  This causes
  NFS to properly handle signals during this VOP on an interruptible
  mount.

PR:		kern/176179
Reported by:	Russell Cattelan (sigdeferstop() recursion)
Reviewed by:	kib
MFC after:	1 month
This commit is contained in:
John Baldwin 2013-02-21 19:02:50 +00:00
parent ae40be8cf0
commit 593efaf9f7
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=247116
11 changed files with 141 additions and 41 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
sys/fs/nfs/nfs_commonkrpc.c
View File

@ -1080,7 +1080,6 @@ newnfs_set_sigmask(struct thread *td, sigset_t *oldset)
SIGDELSET(newset, newnfs_sig_set[i]);
}
mtx_unlock(&p->p_sigacts->ps_mtx);
sigdeferstop(td);
kern_sigprocmask(td, SIG_SETMASK, &newset, oldset,
SIGPROCMASK_PROC_LOCKED);
PROC_UNLOCK(p);
@ -1092,7 +1091,6 @@ newnfs_restore_sigmask(struct thread *td, sigset_t *set)
if (td == NULL)
td = curthread; /* XXX */
kern_sigprocmask(td, SIG_SETMASK, set, NULL, 0);
sigallowstop(td);
}
/*

2
sys/fs/nfsclient/nfs_clvfsops.c
View File

@ -132,7 +132,7 @@ static struct vfsops nfs_vfsops = {
.vfs_unmount = nfs_unmount,
.vfs_sysctl = nfs_sysctl,
};
VFS_SET(nfs_vfsops, nfs, VFCF_NETWORK);
VFS_SET(nfs_vfsops, nfs, VFCF_NETWORK | VFCF_SBDRY);
/* So that loader and kldload(2) can find us, wherever we are.. */
MODULE_VERSION(nfs, 1);

22
sys/kern/kern_sig.c
View File

@ -2537,16 +2537,22 @@ tdsigcleanup(struct thread *td)
}
/* Defer the delivery of SIGSTOP for the current thread. */
void
sigdeferstop(struct thread *td)
/*
* Defer the delivery of SIGSTOP for the current thread. Returns true
* if stops were deferred and false if they were already deferred.
*/
int
sigdeferstop(void)
{
struct thread *td;
KASSERT(!(td->td_flags & TDF_SBDRY),
("attempt to set TDF_SBDRY recursively"));
td = curthread;
if (td->td_flags & TDF_SBDRY)
return (0);
thread_lock(td);
td->td_flags |= TDF_SBDRY;
thread_unlock(td);
return (1);
}
/*
@ -2555,11 +2561,11 @@ sigdeferstop(struct thread *td)
* will suspend either via ast() or a subsequent interruptible sleep.
*/
void
sigallowstop(struct thread *td)
sigallowstop()
{
struct thread *td;
KASSERT(td->td_flags & TDF_SBDRY,
("attempt to clear already-cleared TDF_SBDRY"));
td = curthread;
thread_lock(td);
td->td_flags &= ~TDF_SBDRY;
thread_unlock(td);

2
sys/kern/subr_trap.c
View File

@ -164,6 +164,8 @@ userret(struct thread *td, struct trapframe *frame)
("userret: Returning with with pinned thread"));
KASSERT(td->td_vp_reserv == 0,
("userret: Returning while holding vnode reservation"));
KASSERT((td->td_flags & TDF_SBDRY) == 0,
("userret: Returning with stop signals deferred"));
#ifdef VIMAGE
/* Unfortunately td_vnet_lpush needs VNET_DEBUG. */
VNET_ASSERT(curvnet == NULL,

1
sys/kern/vfs_export.c
View File

@ -49,6 +49,7 @@ __FBSDID("$FreeBSD$");
#include <sys/mutex.h>
#include <sys/rwlock.h>
#include <sys/refcount.h>
#include <sys/signalvar.h>
#include <sys/socket.h>
#include <sys/systm.h>
#include <sys/vnode.h>

2
sys/kern/vfs_lookup.c
View File

@ -339,7 +339,7 @@ namei(struct nameidata *ndp)
auio.uio_offset = 0;
auio.uio_rw = UIO_READ;
auio.uio_segflg = UIO_SYSSPACE;
auio.uio_td = (struct thread *)0;
auio.uio_td = td;
auio.uio_resid = MAXPATHLEN;
error = VOP_READLINK(ndp->ni_vp, &auio, cnp->cn_cred);
if (error) {

2
sys/nfsclient/nfs_krpc.c
View File

@ -748,7 +748,6 @@ nfs_set_sigmask(struct thread *td, sigset_t *oldset)
SIGDELSET(newset, nfs_sig_set[i]);
}
mtx_unlock(&p->p_sigacts->ps_mtx);
sigdeferstop(td);
kern_sigprocmask(td, SIG_SETMASK, &newset, oldset,
SIGPROCMASK_PROC_LOCKED);
PROC_UNLOCK(p);
@ -760,7 +759,6 @@ nfs_restore_sigmask(struct thread *td, sigset_t *set)
if (td == NULL)
td = curthread; /* XXX */
kern_sigprocmask(td, SIG_SETMASK, set, NULL, 0);
sigallowstop(td);
}
/*

2
sys/nfsclient/nfs_vfsops.c
View File

@ -146,7 +146,7 @@ static struct vfsops nfs_vfsops = {
.vfs_unmount = nfs_unmount,
.vfs_sysctl = nfs_sysctl,
};
VFS_SET(nfs_vfsops, oldnfs, VFCF_NETWORK);
VFS_SET(nfs_vfsops, oldnfs, VFCF_NETWORK | VFCF_SBDRY);
/* So that loader and kldload(2) can find us, wherever we are.. */
MODULE_VERSION(oldnfs, 1);

140
sys/sys/mount.h
View File

@ -493,6 +493,7 @@ struct ovfsconf {
#define VFCF_UNICODE 0x00200000 /* stores file names as Unicode */
#define VFCF_JAIL 0x00400000 /* can be mounted from within a jail */
#define VFCF_DELEGADMIN 0x00800000 /* supports delegated administration */
#define VFCF_SBDRY 0x01000000 /* defer stop requests */
typedef uint32_t fsctlop_t;
@ -629,30 +630,121 @@ struct vfsops {
vfs_statfs_t __vfs_statfs;
#define VFS_MOUNT(MP) (*(MP)->mnt_op->vfs_mount)(MP)
#define VFS_UNMOUNT(MP, FORCE) (*(MP)->mnt_op->vfs_unmount)(MP, FORCE)
#define VFS_ROOT(MP, FLAGS, VPP) \
(*(MP)->mnt_op->vfs_root)(MP, FLAGS, VPP)
#define VFS_QUOTACTL(MP, C, U, A) \
(*(MP)->mnt_op->vfs_quotactl)(MP, C, U, A)
#define VFS_STATFS(MP, SBP) __vfs_statfs((MP), (SBP))
#define VFS_SYNC(MP, WAIT) (*(MP)->mnt_op->vfs_sync)(MP, WAIT)
#define VFS_VGET(MP, INO, FLAGS, VPP) \
(*(MP)->mnt_op->vfs_vget)(MP, INO, FLAGS, VPP)
#define VFS_FHTOVP(MP, FIDP, FLAGS, VPP) \
(*(MP)->mnt_op->vfs_fhtovp)(MP, FIDP, FLAGS, VPP)
#define VFS_CHECKEXP(MP, NAM, EXFLG, CRED, NUMSEC, SEC) \
(*(MP)->mnt_op->vfs_checkexp)(MP, NAM, EXFLG, CRED, NUMSEC, SEC)
#define VFS_EXTATTRCTL(MP, C, FN, NS, N) \
(*(MP)->mnt_op->vfs_extattrctl)(MP, C, FN, NS, N)
#define VFS_SYSCTL(MP, OP, REQ) \
(*(MP)->mnt_op->vfs_sysctl)(MP, OP, REQ)
#define VFS_SUSP_CLEAN(MP) \
({if (*(MP)->mnt_op->vfs_susp_clean != NULL) \
(*(MP)->mnt_op->vfs_susp_clean)(MP); })
#define VFS_RECLAIM_LOWERVP(MP, VP) \
({if (*(MP)->mnt_op->vfs_reclaim_lowervp != NULL) \
(*(MP)->mnt_op->vfs_reclaim_lowervp)((MP), (VP)); })
#define VFS_PROLOGUE(MP) do { \
int _enable_stops; \
\
_enable_stops = ((MP) != NULL && \
((MP)->mnt_vfc->vfc_flags & VFCF_SBDRY) && sigdeferstop())
#define VFS_EPILOGUE(MP) \
if (_enable_stops) \
sigallowstop(); \
} while (0)
#define VFS_MOUNT(MP) ({ \
int _rc; \
\
VFS_PROLOGUE(MP); \
_rc = (*(MP)->mnt_op->vfs_mount)(MP); \
VFS_EPILOGUE(MP); \
_rc; })
#define VFS_UNMOUNT(MP, FORCE) ({ \
int _rc; \
\
VFS_PROLOGUE(MP); \
_rc = (*(MP)->mnt_op->vfs_unmount)(MP, FORCE); \
VFS_EPILOGUE(MP); \
_rc; })
#define VFS_ROOT(MP, FLAGS, VPP) ({ \
int _rc; \
\
VFS_PROLOGUE(MP); \
_rc = (*(MP)->mnt_op->vfs_root)(MP, FLAGS, VPP); \
VFS_EPILOGUE(MP); \
_rc; })
#define VFS_QUOTACTL(MP, C, U, A) ({ \
int _rc; \
\
VFS_PROLOGUE(MP); \
_rc = (*(MP)->mnt_op->vfs_quotactl)(MP, C, U, A); \
VFS_EPILOGUE(MP); \
_rc; })
#define VFS_STATFS(MP, SBP) ({ \
int _rc; \
\
VFS_PROLOGUE(MP); \
_rc = __vfs_statfs((MP), (SBP)); \
VFS_EPILOGUE(MP); \
_rc; })
#define VFS_SYNC(MP, WAIT) ({ \
int _rc; \
\
VFS_PROLOGUE(MP); \
_rc = (*(MP)->mnt_op->vfs_sync)(MP, WAIT); \
VFS_EPILOGUE(MP); \
_rc; })
#define VFS_VGET(MP, INO, FLAGS, VPP) ({ \
int _rc; \
\
VFS_PROLOGUE(MP); \
_rc = (*(MP)->mnt_op->vfs_vget)(MP, INO, FLAGS, VPP); \
VFS_EPILOGUE(MP); \
_rc; })
#define VFS_FHTOVP(MP, FIDP, FLAGS, VPP) ({ \
int _rc; \
\
VFS_PROLOGUE(MP); \
_rc = (*(MP)->mnt_op->vfs_fhtovp)(MP, FIDP, FLAGS, VPP); \
VFS_EPILOGUE(MP); \
_rc; })
#define VFS_CHECKEXP(MP, NAM, EXFLG, CRED, NUMSEC, SEC) ({ \
int _rc; \
\
VFS_PROLOGUE(MP); \
_rc = (*(MP)->mnt_op->vfs_checkexp)(MP, NAM, EXFLG, CRED, NUMSEC,\
SEC); \
VFS_EPILOGUE(MP); \
_rc; })
#define VFS_EXTATTRCTL(MP, C, FN, NS, N) ({ \
int _rc; \
\
VFS_PROLOGUE(MP); \
_rc = (*(MP)->mnt_op->vfs_extattrctl)(MP, C, FN, NS, N); \
VFS_EPILOGUE(MP); \
_rc; })
#define VFS_SYSCTL(MP, OP, REQ) ({ \
int _rc; \
\
VFS_PROLOGUE(MP); \
_rc = (*(MP)->mnt_op->vfs_sysctl)(MP, OP, REQ); \
VFS_EPILOGUE(MP); \
_rc; })
#define VFS_SUSP_CLEAN(MP) do { \
if (*(MP)->mnt_op->vfs_susp_clean != NULL) { \
VFS_PROLOGUE(MP); \
(*(MP)->mnt_op->vfs_susp_clean)(MP); \
VFS_EPILOGUE(MP); \
} \
} while (0)
#define VFS_RECLAIM_LOWERVP(MP, VP) do { \
if (*(MP)->mnt_op->vfs_reclaim_lowervp != NULL) { \
VFS_PROLOGUE(MP); \
(*(MP)->mnt_op->vfs_reclaim_lowervp)((MP), (VP)); \
VFS_EPILOGUE(MP); \
} \
} while (0)
#define VFS_KNOTE_LOCKED(vp, hint) do \
{ \

4
sys/sys/signalvar.h
View File

@ -328,8 +328,8 @@ extern struct mtx sigio_lock;
#define SIGPROCMASK_PS_LOCKED 0x0004
int cursig(struct thread *td, int stop_allowed);
void sigdeferstop(struct thread *td);
void sigallowstop(struct thread *td);
int sigdeferstop(void);
void sigallowstop(void);
void execsigs(struct proc *p);
void gsignal(int pgid, int sig, ksiginfo_t *ksi);
void killproc(struct proc *p, char *why);

3
sys/tools/vnode_if.awk
View File

@ -172,6 +172,7 @@ if (cfile) {
"#include <sys/kernel.h>\n" \
"#include <sys/mount.h>\n" \
"#include <sys/sdt.h>\n" \
"#include <sys/signalvar.h>\n" \
"#include <sys/systm.h>\n" \
"#include <sys/vnode.h>\n" \
"\n" \
@ -365,10 +366,12 @@ while ((getline < srcfile) > 0) {
add_debug_code(name, args[i], "Entry", "\t");
printc("\tKTR_START" ctrstr);
add_pre(name);
printc("\tVFS_PROLOGUE(a->a_" args[0]"->v_mount);")
printc("\tif (vop->"name" != NULL)")
printc("\t\trc = vop->"name"(a);")
printc("\telse")
printc("\t\trc = vop->vop_bypass(&a->a_gen);")
printc("\tVFS_EPILOGUE(a->a_" args[0]"->v_mount);")
printc("\tSDT_PROBE(vfs, vop, " name ", return, a->a_" args[0] ", a, rc, 0, 0);\n");
printc("\tif (rc == 0) {");
for (i = 0; i < numargs; ++i)