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Several fixes and improvements to sendfile()

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1.  If we wanted to send exactly as many bytes as the socket buffer is
    sized for, the inner loop of kern_sendfile() would see that the
    socket is full before seeing that it had no more bytes left to send.
    This would cause it to return EAGAIN to the caller instead of
    success.  Fix by changing the order that these conditions are tested.
2.  Simplify the calculation for the bytes to send in each iteration of
    the inner loop of kern_sendfile()
3.  Fix some calls with bogus arguments to sf_buf_ext().  These would
    only trigger on mbuf allocation failure, but would be hilariously
    bad if they did trigger.

Submitted by:	gibbs(3), andre(2)
Reviewed by:	emax, andre
Obtained from:	Netflix
MFC after:	1 week
This commit is contained in:
Scott Long 2013-03-28 14:14:28 +00:00
parent bb44b57367
commit 07dbf2c768
1 changed files with 14 additions and 7 deletions
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21
sys/kern/uipc_syscalls.c
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@ -2115,7 +2115,7 @@ kern_sendfile(struct thread *td, struct sendfile_args *uap,
* Loop and construct maximum sized mbuf chain to be bulk
* dumped into socket buffer.
*/
while (space > loopbytes) {
while (1) {
vm_pindex_t pindex;
vm_offset_t pgoff;
struct mbuf *m0;
@ -2127,15 +2127,12 @@ kern_sendfile(struct thread *td, struct sendfile_args *uap,
* or the passed in nbytes.
*/
pgoff = (vm_offset_t)(off & PAGE_MASK);
xfsize = omin(PAGE_SIZE - pgoff,
obj->un_pager.vnp.vnp_size - uap->offset -
fsbytes - loopbytes);
if (uap->nbytes)
rem = (uap->nbytes - fsbytes - loopbytes);
else
rem = obj->un_pager.vnp.vnp_size -
uap->offset - fsbytes - loopbytes;
xfsize = omin(rem, xfsize);
xfsize = omin(PAGE_SIZE - pgoff, rem);
xfsize = omin(space - loopbytes, xfsize);
if (xfsize <= 0) {
VM_OBJECT_WUNLOCK(obj);
@ -2143,6 +2140,16 @@ kern_sendfile(struct thread *td, struct sendfile_args *uap,
break;
}
/*
* We've already overfilled the socket.
* Let the outer loop figure out how to handle it.
*/
if (space <= loopbytes) {
VM_OBJECT_WUNLOCK(obj);
done = 0;
break;
}
/*
* Attempt to look up the page. Allocate
* if not found or wait and loop if busy.
@ -2249,14 +2256,14 @@ kern_sendfile(struct thread *td, struct sendfile_args *uap,
m0 = m_get((mnw ? M_NOWAIT : M_WAITOK), MT_DATA);
if (m0 == NULL) {
error = (mnw ? EAGAIN : ENOBUFS);
sf_buf_mext((void *)sf_buf_kva(sf), sf);
sf_buf_mext(NULL, sf);
break;
}
if (m_extadd(m0, (caddr_t )sf_buf_kva(sf), PAGE_SIZE,
sf_buf_mext, sfs, sf, M_RDONLY, EXT_SFBUF,
(mnw ? M_NOWAIT : M_WAITOK)) != 0) {
error = (mnw ? EAGAIN : ENOBUFS);
sf_buf_mext((void *)sf_buf_kva(sf), sf);
sf_buf_mext(NULL, sf);
m_freem(m0);
break;
}