between creation of a file descriptor and close(2) when using kernel
assisted threads. What we do is stick descriptors in the table, but
mark them as "larval". This causes essentially everything to treat
it as a non-existent descriptor, except for fdalloc(), which sees a
filled slot so that it won't (incorrectly) allocate it again. When
a descriptor is fully constructed, the code that has constructed it
marks it as "mature" (which actually clears the "larval" flag), and
things continue to work as normal.
While here, gather all the code that gets a descriptor from the table
into a fd_getfile() function, and call it, rather than having the
same (sometimes incorrect) code copied all over the place.
fdexpand(). The former will return ENOSPC if there is not space
in the current filedesc table. The latter performs the expansion
of the filedesc table. This means that fdalloc() won't ever block,
and it gives callers an opportunity to clean up before the
potentially-blocking fdexpand() call.
Update all fdalloc() callers to deal with the need-to-fdexpand() case.
Rewrite unp_externalize() to use fdalloc() and fdexpand() in a
safe way, using an algorithm suggested by Bill Sommerfeld:
- Use a temporary array of integers to hold the new filedesc table
indexes. This allows us to repeat the loop if necessary.
- Loop through the array of file *'s, assigning them to filedesc table
slots. If fdalloc() indicates expansion is necessary, undo the
assignments we've done so far, expand, and retry the whole process.
- Once all file *'s have been assigned to slots, update the f_msgcount
and unp_rights counters.
- Right before we return, copy the temporary integer array to the message
buffer, and trim the length as before.
Note that once locking is added to the filedesc array, this entire
operation will be `atomic', in that the lock will be held while
file *'s are assigned to embryonic table slots, thus preventing anything
else from using them.
descriptor array, which may have blocked. Change callers of
fdalloc() to restart whatever they\'re doing if this condition
happens. (XXX unp_externalize() needs some work, but that will
be tackled later.)
Change finishdup() to close the descriptor in the `new\' slot if
one exists, and change sys_dup2() accordingly.
Closes a race condition when using kernel-assisted user threads.
While here, garbage-collect UF_MAPPED -- it is not used anywhere.
callers and appropriate routines to cope. This makes fo_stat more
consistent with rest of fileops routines and also makes the fo_stat
match FreeBSD as an added bonus.
Discussed with Luke Mewburn on tech-kern@.
use that to inform about way to raise current limit when we reach maximum
number of processes, descriptors or vnodes
XXX hopefully I catched all users of tablefull()
uncleanly due to a lost connection, it would hang in closef() waiting
for the usecount to go back to 1.
An audit of FILE_USE() vs FILE_UNUSE() usage led me to discover some
incorrect error-path code..
In sys_fcntl(), avoid leaking a file descriptor usecount in an error
case of F_SETFL; don't return, instead go to "out" to clean up. I
suspect that the F_SETFL would fail because vop_fcntl is not
implemented in deadfs.
call with F_FSCTL set and F_SETFL calls generate calls to a new
fileop fo_fcntl. Add genfs_fcntl() and soo_fcntl() which return 0
for F_SETFL and EOPNOTSUPP otherwise. Have all leaf filesystems
use genfs_fcntl().
Reviewed by: thorpej
Tested by: wrstuden
count is 0, wait for use count to drain before finishing the close.
This is necessary in order for multiple processes to safely share file
descriptor tables.
limit into account when checking against the limit; fdp->fd_nfiles may
be greater than the current descriptor limit, and there may be space
in fdp->fd_ofiles beyond the limit. If we say it's available,
unp_externalize will get confused and panic when fdalloc fails.
UVM was written by chuck cranor <chuck@maria.wustl.edu>, with some
minor portions derived from the old Mach code. i provided some help
getting swap and paging working, and other bug fixes/ideas. chuck
silvers <chuq@chuq.com> also provided some other fixes.
this is the rest of the MI portion changes.
this will be KNF'd shortly. :-)
to the stat(2) family and msync(2). This uses a primitive function
versioning scheme.
This reverts the libc shared library major version from 13 to 12, and
adds a few new interfaces to bring us to libc version 12.20.
From Frank van der Linden <fvdl@NetBSD.ORG>.
thorpej