Because pipes have no file position. VFS maintained (file) offsets into a
buffer internal to PFS and stored them in vnodes for simplicity, mixing
the responsibilities of filp and vnode objects.
With this patch PFS ignores the position field in REQ_READ and REQ_WRITE
requests making VFS' job a lot simpler.
.sync and fsync used unnecessarily restrictive locking type
.fsync violated locking order by obtaining a vmnt lock after a filp lock
.fsync contained a TOCTOU bug
.new_node violated locking rules (didn't upgrade lock upon file creation)
.do_pipe used unnecessarily restrictive locking type
.always lock pipes exclusively; even a read operation might require to do
a write on a vnode object (update pipe size)
.when opening a file with O_TRUNC, upgrade vnode lock when truncating
.utime used unnecessarily restrictive locking type
.path parsing:
.always acquire VMNT_WRITE or VMNT_EXCL on vmnt and downgrade to
VMNT_READ if that was what was actually requested. This prevents the
following deadlock scenario:
thread A:
lock_vmnt(vmp, TLL_READSER);
lock_vnode(vp, TLL_READSER);
upgrade_vmnt_lock(vmp, TLL_WRITE);
thread B:
lock_vmnt(vmp, TLL_READ);
lock_vnode(vp, TLL_READSER);
thread A will be stuck in upgrade_vmnt_lock and thread B is stuck in
lock_vnode. This happens when, for example, thread A tries create a
new node (open.c:new_node) and thread B tries to do eat_path to
change dir (stadir.c:do_chdir). When the path is being resolved, a
vnode is always locked with VNODE_OPCL (TLL_READSER) and then
downgraded to VNODE_READ if read-only is actually requested. Thread
A locks the vmnt with VMNT_WRITE (TLL_READSER) which still allows
VMNT_READ locks. Thread B can't acquire a lock on the vnode because
thread A has it; Thread A can't upgrade its vmnt lock to VMNT_WRITE
(TLL_WRITE) because thread B has a VMNT_READ lock on it.
By serializing vmnt locks during path parsing, thread B can only
acquire a lock on vmp when thread A has completely finished its
operation.
NetBSD assumes off_t is 64-bit, but on MINIX it is still 32-bit.
So cast the calls to use big_off_t, as stat(2) uses.
Only used in warning messages, was not a real production bug.
. restore state depends on how saving of state was done;
also remember trap style in sig context
. actually set and restore TRACEBIT with new trap styles;
have to remove it once process enters kernel though, done
in debug trap exception handler
. introduce MF_STEP that makes arch-specific code
turn on trace bit instead of setting TRACEBIT directly,
a bit more arch-friendly and avoids keeping precious
state in per-process PSW arch-dependently
state is usually not in p_reg any more with sysenter/syscall trap entries,
so when saving/restarting do_ipc invocations the state has to be remembered
explicitly.
The 'trap style' variable records how a process has trapped into the
kernel (hardware/software interrupt, or one of the other trap
instructions). KTS_NONE indicates the process isn't trapped into the
kernel at all and is useful for sanity checking. The KTS_NONE reset was
inadvertently removed while removing some debugging code and this commit
restores it.
When processes have entered the kernel with one of the new
trap modes, %ebp is not valid, used for stacktraces, so we
need an alternative way to retrieve it to make the stacktraces
valid again.
mount.c: In function 'mount_pfs':
mount.c:395:17: error: variable 'rfp' set but not used [-Werror=unused-but-set-variable]
Change-Id: I2f22590ab4e3a4a1678e9096626ebca53d2660e6
. make vm be able to use malloc() by overriding brk()
and minix_mmap() functions
. phys regions can then be malloc()ed and free()d instead
of being in an avl tree, which is slightly faster
. 'offset' field in phys_region can go too (offset is implied
by position in array) but leads to bigger code changes
Adding the bomb function which takes as a parameter a string
to be printed, print it, cleans up and exits with an error
code. It also means they will exit after the first error, unlike
previous behaviour.
Change-Id: Id0ffdf3938da43586c9dae7c566ee130533c5577
test3 performs tests for null pointers but after that still continues
and uses them. This results in segfault's. Fixing this issue by failing
on the first error.
Also removing minix-config.inc and placing its content in
Makefile.inc, as the file is modified anyway. Simplifies diff.
Change-Id: I6262fdb790a5455b59e07acdccdc221fd5dd41f8
Previously, under some circumstances, the make command could
yield netbsdsrc in other directories than the source directory,
as expected.
This patch fixes this behaviour, by first changing to the expected
directory, and only at the end going back to the original directory.
