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Christoph Lameter demonstrated very poor scalability on the SGI 512-way, with
a many-threaded application which concurrently initializes different parts of
a large anonymous area.
This patch corrects that, by using a separate spinlock per page table page, to
guard the page table entries in that page, instead of using the mm's single
page_table_lock. (But even then, page_table_lock is still used to guard page
table allocation, and anon_vma allocation.)
In this implementation, the spinlock is tucked inside the struct page of the
page table page: with a BUILD_BUG_ON in case it overflows - which it would in
the case of 32-bit PA-RISC with spinlock debugging enabled.
Splitting the lock is not quite for free: another cacheline access. Ideally,
I suppose we would use split ptlock only for multi-threaded processes on
multi-cpu machines; but deciding that dynamically would have its own costs.
So for now enable it by config, at some number of cpus - since the Kconfig
language doesn't support inequalities, let preprocessor compare that with
NR_CPUS. But I don't think it's worth being user-configurable: for good
testing of both split and unsplit configs, split now at 4 cpus, and perhaps
change that to 8 later.
There is a benefit even for singly threaded processes: kswapd can be attacking
one part of the mm while another part is busy faulting.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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In worrying over the various pte operations in different architectures, I came
across some unused functions in UML: remove mprotect_kernel_vm,
protect_vm_page and addr_pte.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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There's usually a good reason when a pte is examined without the lock; but it
makes me nervous when the pointer is dereferenced more than once.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Convert those few architectures which are calling pud_alloc, pmd_alloc,
pte_alloc_map on a user mm, not to take the page_table_lock first, nor drop it
after. Each of these can continue to use pte_alloc_map, no need to change
over to pte_alloc_map_lock, they're neither racy nor swappable.
In the sparc64 io_remap_pfn_range, flush_tlb_range then falls outside of the
page_table_lock: that's okay, on sparc64 it's like flush_tlb_mm, and that has
always been called from outside of page_table_lock in dup_mmap.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Without this patch, uml compile fails with:
LD .tmp_vmlinux1
arch/um/kernel/built-in.o: In function `config_gdb_cb':
arch/um/kernel/tt/gdb.c:129: undefined reference to `TASK_EXTERN_PID'
Tested on i386, but fix needed on x86_64 too AFAICS.
Signed-off-by: Miklos Szeredi <miklos@szeredi.hu>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Missing half of the [PATCH] uml: Fix sysrq-r support for skas mode
We need to remove these (UPT_[DEFG]S) from the read side as well as the
write one - otherwise it simply won't build.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Acked-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Acked-by: Jeff Dike <jdike@addtoit.com>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Give an empty definition for clear_can_do_skas() when it is not needed.
Thanks to Junichi Uekawa <dancer@netfort.gr.jp> for reporting the
breakage and providing a fix (I re-fixed it in an IMHO cleaner way).
Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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The patch to use host AIO support that I submitted early after 2.6.13 exposed
some problems in the block driver. I have fixes for these, but am not
comfortable putting them into 2.6.14 at this late date. So, this patch reverts
the use of host AIO.
I will resubmit the original patch, plus fixes to the driver after 2.6.14
in order to get a reasonable amount of testing before they're exposed to
the general public.
Signed-off-by: Jeff Dike <jdike@addtoit.com>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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UML/x86_64 doesn't run when built with frame pointers disabled. There
was an implicit frame pointer assumption in the stub segfault handler.
With frame pointers disabled, UML dies on handling its first page fault.
The container-of part of this is from Paolo Giarrusso <blaisorblade@yahoo.it>.
Signed-off-by: Jeff Dike <jdike@addtoit.com>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Fix whitespace - I split this off the previous patch for easier review.
Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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After restoring the existing code, make it work also when included in
kernelspace code (which isn't currently the case, but at least this will prevent
people from "fixing" it as just happened).
Whitespace is fixed in next patch - it cluttered the diff too much.
Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Commit 44456d37b59d8e541936ed26d8b6e08d27e88ac1, between 2.6.13-rc3 and -rc4,
was a "nice cleanup" which broke something. Revert the offending part.
It broke because:
a) because this part doesn't fall under the description
b) the author didn't know what he was doing here
c) the author didn't try to compile the existing code and see that it worked
perfectly.
d) the author didn't ask us what was happening
e) you didn't either, and somebody there should have learned that UML is a bit
different.
In fact, UML is special in linking to host libc and using its includes.
In particular, since host includes always define both __BIG_ENDIAN and
__LITTLE_ENDIAN, ntohll() macros started thinking to be in a big-endian world;
and on-disk compatibility was broken.
Many thanks go to Nix for reporting the problem and correctly diagnosing an
endianness problem.
Btw, this patch restores the previous code, which worked; but the definitions
would be uncorrect if used in kernelspace files.
Next patch addresses that.
Cc: Nix <nix@esperi.org.uk>, Olaf Hering <olh@suse.de>
Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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For files which need to include glibc headers (i.e. userspace files), we
specified the correct flags only for .o, not for .s/.lst/.i. Fix this.
Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Too many people were confused by skas0 and tried using "mode=skas0". And after
all, they are right - accept this.
Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Add a missing $(Q) to a "ln" invocation.
Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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The old code had the IP and SP coming from the registers in the thread
struct, which are completely wrong since those are the userspace
registers. This fixes that by pulling the correct values from the
jmp_buf in which the kernel state of each thread is stored.
Signed-off-by: Allan Graves <allan.graves@oracle.com>
Signed-off-by: Jeff Dike <jdike@addtoit.com>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Al's build tidying missed one bit from me - without this UML doesn't boot.
Signed-off-by: Jeff Dike <jdike@addtoit.com>
Acked-by: Al Viro <viro@ftp.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Revert commit 12ebcd73e40e09f0dfddf89e465cc0541e0ff8b1, i.e. [PATCH] uml: run
mconsole "sysrq" in process context on request from Jeff Dike.
a) sysrq may be run when the scheduler is non-functioning
b) the warning I wanted to fix actually came from the fault handler run in
atomic context. But I fixed that not to take the semaphore in a separate
patch.
c) the fault handler is run because of a fault, and that fault was
unaffected by this patch.
Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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SEGV_MAYBE_FIXABLE tests ptrace_faultinfo, and depends on it being 1 only in
SKAS3 mode, while currently when running with mode=tt it will be 1 anyway.
Fix this, and do the same for proc_mm.
Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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I hadn't been running a SKAS3 host when testing the "uml: fix hang in TT mode
on fault" patch (commit 546fe1cbf91d4d62e3849517c31a2327c992e5c5), and I
didn't think enough to the missing trap_no in SKAS3 mode.
In fact, the resulting kernel doesn't work at all in SKAS3 mode.
Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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UML makefiles sanitized:
- number of generated headers reduced to 2 (from user-offsets.c and
kernel-offsets.c resp.). The rest is made constant and simply
includes those two.
- mk_... helpers are gone now that we don't need to generate these
headers
- arch/um/include2 removed since everything under arch/um/include/sysdep
is constant now and symlink can point straight to source tree.
- dependencies seriously simplified.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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failure
User get *a lot* confused when consoles don't work but we don't report
anything. And, as reported in the comment, using printk to report "your
console doesn't work" isn't likely to go that far.
Fix the problem on the base of this: stack consumption by host printf(). Use
kernel sprintf() and os_write_file, using a wild guess that one page will be
enough for the message, to preallocate the buffer with kmalloc().
Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Cc: Jeff Dike <jdike@addtoit.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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setup_initial_poll is only called with sigio_lock() held, so use appropriate
allocation.
Also, parse_chan() can also be called when holding a spinlock (see line_open()
-> parse_chan_pair()).
I have sporadic problems (spinlock taken twice, with spinlock debugging on UP)
which could be caused by a sequence like "take spinlock, alloc and go to
sleep, take again the spinlock in the other thread".
Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Cc: Jeff Dike <jdike@addtoit.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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GFP_ATOMIC | GFP_KERNEL is meaningless and won't work. Actually it never
worked, even in 2.4.
Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Cc: Jeff Dike <jdike@addtoit.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Following i386, we should maybe refuse trying to fault in pages when we're
doing atomic operations, because to handle the fault we could need to take
already taken spinlocks.
Also, if we're doing an atomic operation (in the sense of in_atomic()) we're
surely in kernel mode and we're surely going to handle adequately the failed
fault, so it's safe to behave this way.
Currently, on UML SMP is rarely used, and we don't support PREEMPT, so this is
unlikely to create problems right now, but it might in the future.
Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Cc: Jeff Dike <jdike@addtoit.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Things are breaking horribly with sysrq called in interrupt context. I want
to try to fix it, but probably this is simpler. To tell the truth, sysrq is
normally run in interrupt context, so there shouldn't be any problem.
There's also a warning from the fault handler because it's run in atomic
context (I have a patch for that, only I deferred it). This is why I'm doing
this.
Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Cc: Jeff Dike <jdike@addtoit.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Avoid setting w = 0 twice. Spotted this (trivial) thing which is needed for
another patch.
Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Cc: Jeff Dike <jdike@addtoit.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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The current code doesn't handle well general protection faults on the host -
it thinks that cr2 is always the address of a page fault. While actually, on
general protection faults, that address is not accessible, so we'd better
assume we couldn't satisfy the fault. Currently instead we think we've fixed
it, so we go back, retry the instruction and fault again endlessly.
This leads to the kernel hanging when doing copy_from_user(dest, -1, ...) in
TT mode, since reading *(-1) causes a GFP, and we don't support kernel
preemption.
Thanks to Luo Xin for testing UML with LTP and reporting the failures he got.
Cc: Luo Xin <luothing@sina.com>
Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Cc: Jeff Dike <jdike@addtoit.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Simplify the code by using strlcat() instead of strncat() and manual
appending.
Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Cc: Jeff Dike <jdike@addtoit.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Only remove the UML pidfile and management socket if we created them.
Currently in case two UMLs are started with the same umid, the second will
remove the first's ones.
Probably we should also panic() at that point, not sure however.
Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Cc: Jeff Dike <jdike@addtoit.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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The header declaring this function wasn't included, so the function declaration
was totally bogus wrt. the proto - even if this wasn't going to fail at all.
It was so bad that the compile warning I got was "control reaches end of
non-void function", i.e. missing return. Actually, this has been there for ages,
the consolidation patch just added the warning which was needed to clean it up.
Nice. Really.
Cc: Allan Graves <allan.graves@gmail.com>
Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Explain why the casting we do to silence this warning is indeed safe.
It is because the field we're casting from, though being 64-bit wide, was filled
with a pointer in first place by ourselves.
Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Readd this header (deleted in 60d339f6fe0831060600c62418b71a62ad26c281). A
warning is spit out here about undeclared getpgrp().
Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Even if with a bit of misunderstanding, Al fixed this in commit
95608261dae863bc43292e6fbd946a3abd3aa49f.
Well, the symbol was intended to come from userspace (it exists there on normal
host), but since some hosts may miss that, using the kernel one is just as fine.
However, rename it to be named consistently with the rest.
Actually, he missed converting ELFCLASS32 to coming from kernel headers. For
consistence, add ELFCLASS64 too.
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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gcc is now complaining during link on some hosts - fix it as for other things.
Reported by Antoine Martin <antoine@nagafix.co.uk>.
Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Translate uname output taken from the host if needed.
Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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I am a lamer :-(. Luckily, Luo Xin performed LTP testing and found this failure.
Btw, the fact that the patch in which I introduced this was merged shows that:
a) I'm really trusted by people
b) sometimes they're wrong about point a).
c) lack of time for reviewers.
CC: Luo Xin <luothing@sina.com>
Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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When removing verify_area, verify_area_{tt,skas} were forgotten.
Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Using native cmpxchg offers a slight performance improvement in uml/i386.
Signed-off-by: Jeff Dike <jdike@addtoit.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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asm/elf.h is bad on x86_64, and i386 doesn't need it any more after Al's
cleanup.
Signed-off-by: Jeff Dike <jdike@addtoit.com>
Cc: Paolo Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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do_aio used to return -1 on error instead of errno.
Signed-off-by: Jeff Dike <jdike@addtoit.com>
Cc: Paolo Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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The serial UML OS-abstraction layer patch (um/kernel dir).
This joins mem_user.c and mem.c files.
Signed-off-by: Gennady Sharapov <Gennady.V.Sharapov@intel.com>
Signed-off-by: Jeff Dike <jdike@addtoit.com>
Cc: Paolo Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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The serial UML OS-abstraction layer patch (um/kernel dir).
This moves all system calls from mem_user.c and tempfile.c files under
os-Linux dir.
Signed-off-by: Gennady Sharapov <Gennady.V.Sharapov@intel.com>
Signed-off-by: Jeff Dike <jdike@addtoit.com>
Cc: Paolo Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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The poster child for this patch is the third tuntap_user hunk. When an ioctl
fails, it properly closes the opened file descriptor and returns. However,
the close resets errno to 0, and the 'return errno' that follows returns 0
rather than the value that ioctl set. This caused the caller to believe that
the device open succeeded and had opened file descriptor 0, which caused no
end of interesting behavior.
The rest of this patch is a pass through the UML sources looking for places
where errno could be reset before being passed back out. A common culprit is
printk, which could call write, being called before errno is returned.
In some cases, where the code ends up being much smaller, I just deleted the
printk.
There was another case where a caller of run_helper looked at errno after a
failure, rather than the return value of run_helper, which was the errno value
that it wanted.
Signed-off-by: Jeff Dike <jdike@addtoit.com>
Cc: Paolo Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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These ugly double-casts are the result of gdb complaining about size
Signed-off-by: Jeff Dike <jdike@addtoit.com>
Cc: Paolo Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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linux/inet.h isn't needed, and on my system, is empty.
Signed-off-by: Jeff Dike <jdike@addtoit.com>
Cc: Paolo Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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This removes a file which is no longer used.
Signed-off-by: Jeff Dike <jdike@addtoit.com>
Cc: Paolo Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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This patch implements a stack trace for a thread, not unlike sysrq-t does.
The advantage to this is that a break point can be placed on showreqs, so that
upon showing the stack, you jump immediately into the debugger. While sysrq-t
does the same thing, sysrq-t shows *all* threads stacks. It also doesn't work
right now. In the future, I thought it might be acceptable to make this show
all pids stacks, but perhaps leaving well enough alone and just using sysrq-t
would be okay. For now, upon receiving the stack command, UML switches
context to that thread, dumps its registers, and then switches context back to
the original thread. Since UML compacts all threads into one of 4 host
threads, this sort of mechanism could be expanded in the future to include
other debugging helpers that sysrq does not cover.
Note by jdike - The main benefit to this is that it brings an arbitrary thread
back into context, where it can be examined by gdb. The fact that it dumps it
stack is secondary. This provides the capability to examine a sleeping
thread, which has existed in tt mode, but not in skas mode until now.
Also, the other threads, that sysrq doesn't cover, can be gdb-ed directly
anyway.
Signed-off-by: Allan Graves<allan.graves@gmail.com>
Signed-off-by: Jeff Dike <jdike@addtoit.com>
Cc: Paolo Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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