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[MAJOR] spec I/O: fix allocations of spec entries for an FD

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Under some circumstances, it was possible with speculative I/O to
reallocate multiple entries for the same FD if an fd_{set,clr,set}
or fd_{clr,set,clr} sequences were performed before a schedule.

Fix this by keeping a an allocation flag for each fd.
This commit is contained in:
Willy Tarreau 2007-08-31 17:01:18 +02:00
parent e7150cdcfa
commit 4eac209555
1 changed files with 22 additions and 12 deletions
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34
src/ev_sepoll.c
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@ -115,7 +115,7 @@ static _syscall4 (int, epoll_wait, int, epfd, struct epoll_event *, events, int,
* FIXME: should be a bit field */
struct fd_status {
unsigned int e:4; // read and write events status.
unsigned int s:28; // Position in spec list. Should be last.
unsigned int s1:28; // Position in spec list+1. 0=not in list. Should be last.
};
static int nbspec = 0; // current size of the spec list
@ -135,27 +135,37 @@ static struct epoll_event ev;
REGPRM1 static void alloc_spec_entry(const int fd)
{
if (fd_list[fd].e & FD_EV_RW_SL)
if (fd_list[fd].s1)
return;
fd_list[fd].s = nbspec;
spec_list[nbspec++] = fd;
fd_list[fd].s1 = nbspec + 1;
spec_list[nbspec] = fd;
nbspec++;
}
/* removes entry <pos> from the spec list and replaces it with the last one.
* The fd_list is adjusted to match the back reference if needed.
/* Removes entry used by fd <fd> from the spec list and replaces it with the
* last one. The fd_list is adjusted to match the back reference if needed.
* If the fd has no entry assigned, return immediately.
*/
REGPRM1 static void delete_spec_entry(const int pos)
REGPRM1 static void release_spec_entry(int fd)
{
int fd;
unsigned int pos;
pos = fd_list[fd].s1;
if (!pos)
return;
fd_list[fd].s1 = 0;
pos--;
/* we have spec_list[pos]==fd */
nbspec--;
if (pos == nbspec)
return;
/* we replace current FD by the highest one */
/* we replace current FD by the highest one, which may sometimes be the same */
fd = spec_list[nbspec];
fd_list[fd].s1 = pos + 1;
spec_list[pos] = fd;
fd_list[fd].s = pos;
}
/*
@ -234,7 +244,7 @@ REGPRM1 static void __fd_rem(int fd)
REGPRM1 static void __fd_clo(int fd)
{
if (fd_list[fd].e & FD_EV_RW_SL)
delete_spec_entry(fd_list[fd].s);
release_spec_entry(fd);
fd_list[fd].e &= ~(FD_EV_MASK);
}
@ -346,7 +356,7 @@ REGPRM2 static void _do_poll(struct poller *p, struct timeval *exp)
/* This fd switched to combinations of either WAIT or
* IDLE. It must be removed from the spec list.
*/
delete_spec_entry(spec_idx);
release_spec_entry(fd);
continue;
}
}