Put all the "rewrite and check section headers" in one place. This
adds another iteration over the sections, but it's far clearer. We
iterate once for every find_section() so we already iterate over many
times.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Btw, here's a patch that _looks_ large, but it really pretty trivial, and
sets things up so that it would be way easier to split off pieces of the
module loading.
The reason it looks large is that it creates a "module_info" structure
that contains all the module state that we're building up while loading,
instead of having individual variables for all the indices etc.
So the patch ends up being large, because every "symindex" access instead
becomes "info.index.sym" etc. That may be a few characters longer, but it
then means that we can just pass a pointer to that "info" structure
around. and let all the pieces fill it in very naturally.
As an example of that, the patch also moves the initialization of all
those convenience variables into a "setup_module_info()" function. And at
this point it really does become very natural to start to peel off some of
the error labels and move them into the helper functions - now the
"truncated" case is gone, and is handled inside that setup function
instead.
So maybe you don't like this approach, and it does make the variable
accesses a bit longer, but I don't think unreadably so. And the patch
really does look big and scary, but there really should be absolutely no
semantic changes - most of it was a trivial and mindless rename.
In fact, it was so mindless that I on purpose kept the existing helper
functions looking like this:
- err = check_modinfo(mod, sechdrs, infoindex, versindex);
+ err = check_modinfo(mod, info.sechdrs, info.index.info, info.index.vers);
rather than changing them to just take the "info" pointer. IOW, a second
phase (if you think the approach is ok) would change that calling
convention to just do
err = check_modinfo(mod, &info);
(and same for "layout_sections()", "layout_symtabs()" etc.) Similarly,
while right now it makes things _look_ bigger, with things like this:
versindex = find_sec(hdr, sechdrs, secstrings, "__versions");
becoming
info->index.vers = find_sec(info->hdr, info->sechdrs, info->secstrings, "__versions");
in the new "setup_module_info()" function, that's again just a result of
it being a search-and-replace patch. By using the 'info' pointer, we could
just change the 'find_sec()' interface so that it ends up being
info->index.vers = find_sec(info, "__versions");
instead, and then we'd actually have a shorter and more readable line. So
for a lot of those mindless variable name expansions there's would be room
for separate cleanups.
I didn't move quite everything in there - if we do this to layout_symtabs,
for example, we'd want to move the percpu, symoffs, stroffs, *strmap
variables to be fields in that module_info structure too. But that's a
much smaller patch, I moved just the really core stuff that is currently
being set up and used in various parts.
But even in this rough form, it removes close to 70 lines from that
function (but adds 22 lines overall, of course - the structure definition,
the helper function declarations and call-sites etc etc).
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
And now that I'm looking at that call-chain (to see if it would make sense
to use some other more specific lock - doesn't look like it: all the
readers are using RCU and this is the only writer), I also give you this
trivial one-liner. It changes each_symbol() to not put that constant array
on the stack, resulting in changing
movq $C.388.31095, %rsi #, tmp85
subq $376, %rsp #,
movq %rdi, %rbx # fn, fn
leaq -208(%rbp), %rdi #, tmp84
movq %rbx, %rdx # fn,
rep movsl
xorl %esi, %esi #
leaq -208(%rbp), %rdi #, tmp87
movq %r12, %rcx # data,
call each_symbol_in_section.clone.0 #
into
xorl %esi, %esi #
subq $216, %rsp #,
movq %rdi, %rbx # fn, fn
movq $arr.31078, %rdi #,
call each_symbol_in_section.clone.0 #
which is not so much about being obviously shorter and simpler because we
don't unnecessarily copy that constant array around onto the stack, but
also about having a much smaller stack footprint (376 vs 216 bytes - see
the update of 'rsp').
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
1) Extract out the relocation loop into apply_relocations
2) Extract license and version checks into check_module_license_and_versions
3) Extract icache flushing into flush_module_icache
4) Move __obsparm warning into find_module_sections
5) Move license setting into check_modinfo.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Allocate references inside module_unload_init(), clean up inside
module_unload_free().
This version fixed to do allocation before __this_cpu_write, thanks to
bug reports from linux-next from Dave Young <hidave.darkstar@gmail.com>
and Stephen Rothwell <sfr@canb.auug.org.au>.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Here's a second one. It's slightly less trivial - since we now have error
cases - and equally untested so it may well be totally broken. But it also
cleans up a bit more, and avoids one of the goto targets, because the
"move_module()" helper now does both allocations or none.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
I'd start from the trivial stuff. There's a fair amount of straight-line
code that just makes the function hard to read just because you have to
page up and down so far. Some of it is trivial to just create a helper
function for.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
No need to clear mod->refptr in module_unload_init(), since
alloc_percpu() already clears allocated chunks.
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> (removed unused var)
The command
echo "file ec.c +p" >/sys/kernel/debug/dynamic_debug/control
causes an oops.
Move the call to ddebug_remove_module() down into free_module(). In this
way it should be called from all error paths. Currently, we are missing
the remove if the module init routine fails.
Signed-off-by: Jason Baron <jbaron@redhat.com>
Reported-by: Thomas Renninger <trenn@suse.de>
Tested-by: Thomas Renninger <trenn@suse.de>
Cc: <stable@kernel.org> [2.6.32+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
We should initialize the module dynamic debug datastructures
only after determining that the module is not loaded yet. This
fixes a bug that introduced in 2.6.35-rc2, where when a trying
to load a module twice, we also load it's dynamic printing data
twice which causes all sorts of nasty issues. Also handle
the dynamic debug cleanup later on failure.
Signed-off-by: Yehuda Sadeh <yehuda@hq.newdream.net>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> (removed a #ifdef)
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Problem: it's hard to avoid an init routine stumbling over a
request_module these days. And it's not clear it's always a bad idea:
for example, a module like kvm with dynamic dependencies on kvm-intel
or kvm-amd would be neater if it could simply request_module the right
one.
In this particular case, it's libcrc32c:
libcrc32c_mod_init
crypto_alloc_shash
crypto_alloc_tfm
crypto_find_alg
crypto_alg_mod_lookup
crypto_larval_lookup
request_module
If another module is waiting inside resolve_symbol() for libcrc32c to
finish initializing (ie. bne2 depends on libcrc32c) then it does so
holding the module lock, and our request_module() can't make progress
until that is released.
Waiting inside resolve_symbol() without the lock isn't all that hard:
we just need to pass the -EBUSY up the call chain so we can sleep
where we don't hold the lock. Error reporting is a bit trickier: we
need to copy the name of the unfinished module before releasing the
lock.
Other notes:
1) This also fixes a theoretical issue where a weak dependency would allow
symbol version mismatches to be ignored.
2) We rename use_module to ref_module to make life easier for the only
external user (the out-of-tree ksplice patches).
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Tim Abbot <tabbott@ksplice.com>
Tested-by: Brandon Philips <bphilips@suse.de>
It disabled preempt so it was "safe", but nothing stops another module
slipping in before this module is added to the global list now we don't
hold the lock the whole time.
So we check this just after we check for duplicate modules, and just
before we put the module in the global list.
(find_symbol finds symbols in coming and going modules, too).
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
I think Rusty may have made the lock a bit _too_ finegrained there, and
didn't add it to some places that needed it. It looks, for example, like
PATCH 1/2 actually drops the lock in places where it's needed
("find_module()" is documented to need it, but now load_module() didn't
hold it at all when it did the find_module()).
Rather than adding a new "module_loading" list, I think we should be able
to just use the existing "modules" list, and just fix up the locking a
bit.
In fact, maybe we could just move the "look up existing module" a bit
later - optimistically assuming that the module doesn't exist, and then
just undoing the work if it turns out that we were wrong, just before
adding ourselves to the list.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Kay Sievers <kay.sievers@vrfy.org> reports that we still have some
contention over module loading which is slowing boot.
Linus also disliked a previous "drop lock and regrab" patch to fix the
bne2 "gave up waiting for init of module libcrc32c" message.
This is more ambitious: we only grab the lock where we need it.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: Brandon Philips <brandon@ifup.org>
Cc: Kay Sievers <kay.sievers@vrfy.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
These were placed in the header in ef665c1a06 to get the various
SYSFS/MODULE config combintations to compile.
That may have been necessary then, but it's not now. These functions
are all local to module.c.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: Randy Dunlap <randy.dunlap@oracle.com>
This means a little extra work, but is more logical: we don't put
anything in sysfs until we're about to put the module into the
global list an parse its parameters.
This also gives us a logical place to put duplicate module detection
in the next patch.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
When adding a module that depends on another one, we used to create a
one-way list of "modules_which_use_me", so that module unloading could
see who needs a module.
It's actually quite simple to make that list go both ways: so that we
not only can see "who uses me", but also see a list of modules that are
"used by me".
In fact, we always wanted that list in "module_unload_free()": when we
unload a module, we want to also release all the other modules that are
used by that module. But because we didn't have that list, we used to
first iterate over all modules, and then iterate over each "used by me"
list of that module.
By making the list two-way, we simplify module_unload_free(), and it
allows for some trivial fixes later too.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> (cleaned & rebased)
* 'for-35' of git://repo.or.cz/linux-kbuild: (81 commits)
kbuild: Revert part of e8d400a to resolve a conflict
kbuild: Fix checking of scm-identifier variable
gconfig: add support to show hidden options that have prompts
menuconfig: add support to show hidden options which have prompts
gconfig: remove show_debug option
gconfig: remove dbg_print_ptype() and dbg_print_stype()
kconfig: fix zconfdump()
kconfig: some small fixes
add random binaries to .gitignore
kbuild: Include gen_initramfs_list.sh and the file list in the .d file
kconfig: recalc symbol value before showing search results
.gitignore: ignore *.lzo files
headerdep: perlcritic warning
scripts/Makefile.lib: Align the output of LZO
kbuild: Generate modules.builtin in make modules_install
Revert "kbuild: specify absolute paths for cscope"
kbuild: Do not unnecessarily regenerate modules.builtin
headers_install: use local file handles
headers_check: fix perl warnings
export_report: fix perl warnings
...
Rafael sees a sometimes crash at precpu_modfree from kernel/module.c; it
only occurred with another (since-reverted) patch, but that patch simply
changed timing to uncover this bug, it was otherwise unrelated.
The comment about the mod being freed is self-explanatory, but neither
Tejun nor I read it. This bug was introduced in 259354deaa, after it
had previously been fixed in 6e2b75740b. How embarrassing.
Reported-by: "Rafael J. Wysocki" <rjw@sisk.pl>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Embarrassingly-Acked-by: Tejun Heo <tj@kernel.org>
Cc: Masami Hiramatsu <mhiramat@redhat.com>
Tested-by: "Rafael J. Wysocki" <rjw@sisk.pl>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This reverts commit 480b02df3a, since
Rafael reports that it causes occasional kernel paging request faults in
load_module().
Dropping the module lock and re-taking it deep in the call-chain is
definitely not the right thing to do. That just turns the mutex from a
lock into a "random non-locking data structure" that doesn't actually
protect what it's supposed to protect.
Requested-and-tested-by: Rafael J. Wysocki <rjw@sisk.pl>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Brandon Philips <brandon@ifup.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* 'modules' of git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux-2.6-for-linus:
module: drop the lock while waiting for module to complete initialization.
MODULE_DEVICE_TABLE(isapnp, ...) does nothing
hisax_fcpcipnp: fix broken isapnp device table.
isapnp: move definitions to mod_devicetable.h so file2alias can reach them.
* 'kdb-merge' of git://git.kernel.org/pub/scm/linux/kernel/git/jwessel/linux-2.6-kgdb: (25 commits)
kdb,debug_core: Allow the debug core to receive a panic notification
MAINTAINERS: update kgdb, kdb, and debug_core info
debug_core,kdb: Allow the debug core to process a recursive debug entry
printk,kdb: capture printk() when in kdb shell
kgdboc,kdb: Allow kdb to work on a non open console port
kgdb: Add the ability to schedule a breakpoint via a tasklet
mips,kgdb: kdb low level trap catch and stack trace
powerpc,kgdb: Introduce low level trap catching
x86,kgdb: Add low level debug hook
kgdb: remove post_primary_code references
kgdb,docs: Update the kgdb docs to include kdb
kgdboc,keyboard: Keyboard driver for kdb with kgdb
kgdb: gdb "monitor" -> kdb passthrough
sparc,sunzilog: Add console polling support for sunzilog serial driver
sh,sh-sci: Use NO_POLL_CHAR in the SCIF polled console code
kgdb,8250,pl011: Return immediately from console poll
kgdb: core changes to support kdb
kdb: core for kgdb back end (2 of 2)
kdb: core for kgdb back end (1 of 2)
kgdb,blackfin: Add in kgdb_arch_set_pc for blackfin
...
