Simplify UIO_SYSSPACE and UIO_NOCOPY paths in uiomove
Uiomove can only block when the segflag is UIO_USERSPACE, otherwise we end up just doing a bcopy (or nothing) and moving cursors. So only emit witness warnings and set deadlock thread flags in the UIO_USERSPACE case. Reviewed by: kib Sponsored by: Netflix Differential Revision: https://reviews.freebsd.org/D11489
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Notes:
svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=320738
@ -206,31 +206,32 @@ uiomove_nofault(void *cp, int n, struct uio *uio)
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static int
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uiomove_faultflag(void *cp, int n, struct uio *uio, int nofault)
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{
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struct thread *td;
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struct iovec *iov;
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size_t cnt;
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int error, newflags, save;
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td = curthread;
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error = 0;
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KASSERT(uio->uio_rw == UIO_READ || uio->uio_rw == UIO_WRITE,
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("uiomove: mode"));
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KASSERT(uio->uio_segflg != UIO_USERSPACE || uio->uio_td == td,
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KASSERT(uio->uio_segflg != UIO_USERSPACE || uio->uio_td == curthread,
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("uiomove proc"));
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if (!nofault)
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WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, NULL,
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"Calling uiomove()");
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/* XXX does it make a sense to set TDP_DEADLKTREAT for UIO_SYSSPACE ? */
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newflags = TDP_DEADLKTREAT;
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if (uio->uio_segflg == UIO_USERSPACE && nofault) {
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/*
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* Fail if a non-spurious page fault occurs.
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*/
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newflags |= TDP_NOFAULTING | TDP_RESETSPUR;
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if (uio->uio_segflg == UIO_USERSPACE) {
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newflags = TDP_DEADLKTREAT;
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if (nofault) {
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/*
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* Fail if a non-spurious page fault occurs.
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*/
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newflags |= TDP_NOFAULTING | TDP_RESETSPUR;
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} else {
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WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, NULL,
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"Calling uiomove()");
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}
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save = curthread_pflags_set(newflags);
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} else {
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KASSERT(nofault == 0, ("uiomove: nofault"));
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}
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save = curthread_pflags_set(newflags);
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while (n > 0 && uio->uio_resid) {
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iov = uio->uio_iov;
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@ -272,7 +273,8 @@ uiomove_faultflag(void *cp, int n, struct uio *uio, int nofault)
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n -= cnt;
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}
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out:
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curthread_pflags_restore(save);
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if (uio->uio_segflg == UIO_USERSPACE)
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curthread_pflags_restore(save);
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return (error);
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}
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