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Make the tty vmin/vtime timeouts work for hz > 169 on 32 bit machines.

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This commit is contained in:
peter 2005-03-12 00:10:23 +00:00
parent f5d07b2dc9
commit eca731ac63
1 changed files with 7 additions and 7 deletions
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14
sys/kern/tty.c
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@ -97,6 +97,7 @@ __FBSDID("$FreeBSD$");
#include <sys/poll.h>
#include <sys/kernel.h>
#include <sys/vnode.h>
#include <sys/limits.h>
#include <sys/serial.h>
#include <sys/signalvar.h>
#include <sys/resourcevar.h>
@ -1854,14 +1855,13 @@ ttread(struct tty *tp, struct uio *uio, int flag)
#undef diff
/*
* Rounding down may make us wake up just short
* of the target, so we round up.
* The formula is ceiling(slp * hz/1000000).
* 32-bit arithmetic is enough for hz < 169.
* XXX see tvtohz() for how to avoid overflow if hz
* is large (divide by `tick' and/or arrange to
* use tvtohz() if hz is large).
* of the target, so we round up. The 32 bit arithmetic is
* sufficient for the first calculation for hz < 169.
*/
slp = (long) (((u_long)slp * hz) + 999999) / 1000000;
if (sizeof(u_long) > 4 || slp <= ULONG_MAX / hz)
slp = (long) (((u_long)slp * hz) + 999999) / 1000000;
else
slp = (slp + (tick - 1)) / tick;
goto sleep;
}
if (qp->c_cc <= 0) {