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  1. 15 May, 2020 17 commits
  3. 13 May, 2020 1 commit
    • Gustavo A. R. Silva's avatar
      greybus: Replace zero-length array with flexible-array · 84c1e51d
      Gustavo A. R. Silva authored 
      The current codebase makes use of the zero-length array language
extension to the C90 standard, but the preferred mechanism to declare
variable-length types such as these ones is a flexible array member[1][2],
introduced in C99:

struct foo {
        int stuff;
        struct boo array[];
};

By making use of the mechanism above, we will get a compiler warning
in case the flexible array does not occur last in the structure, which
will help us prevent some kind of undefined behavior bugs from being
inadvertently introduced[3] to the codebase from now on.

Also, notice that, dynamic memory allocations won't be affected by
this change:

"Flexible array members have incomplete type, and so the sizeof operator
may not be applied. As a quirk of the original implementation of
zero-length arrays, sizeof evaluates to zero."[1]

sizeof(flexible-array-member) triggers a warning because flexible array
members have incomplete type[1]. There are some instances of code in
which the sizeof operator is being incorrectly/erroneously applied to
zero-length arrays and the result is zero. Such instances may be hiding
some bugs. So, this work (flexible-array member conversions) will also
help to get completely rid of those sorts of issues.

This issue was found with the help of Coccinelle.

[1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html
[2] https://github.com/KSPP/linux/issues/21
[3] commit 76497732 ("cxgb3/l2t: Fix undefined behaviour")
Signed-off-by: default avatarGustavo A. R. Silva <gustavoars@kernel.org>
Link: https://lore.kernel.org/r/20200507185318.GA14393@embeddedorSigned-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      84c1e51d
  5. 11 May, 2020 1 commit
  7. 10 May, 2020 7 commits
    • Linus Torvalds's avatar
      Linux 5.7-rc5 · 2ef96a5b
      Linus Torvalds authored
      2ef96a5b
    • Linus Torvalds's avatar
      Merge tag 'x86-urgent-2020-05-10' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip · c14cab26
      Linus Torvalds authored 
      Pull x86 fixes from Thomas Gleixner:
 "A set of fixes for x86:

   - Ensure that direct mapping alias is always flushed when changing
     page attributes. The optimization for small ranges failed to do so
     when the virtual address was in the vmalloc or module space.

   - Unbreak the trace event registration for syscalls without arguments
     caused by the refactoring of the SYSCALL_DEFINE0() macro.

   - Move the printk in the TSC deadline timer code to a place where it
     is guaranteed to only be called once during boot and cannot be
     rearmed by clearing warn_once after boot. If it's invoked post boot
     then lockdep rightfully complains about a potential deadlock as the
     calling context is different.

   - A series of fixes for objtool and the ORC unwinder addressing
     variety of small issues:

       - Stack offset tracking for indirect CFAs in objtool ignored
         subsequent pushs and pops

       - Repair the unwind hints in the register clearing entry ASM code

       - Make the unwinding in the low level exit to usermode code stop
         after switching to the trampoline stack. The unwind hint is no
         longer valid and the ORC unwinder emits a warning as it can't
         find the registers anymore.

       - Fix unwind hints in switch_to_asm() and rewind_stack_do_exit()
         which caused objtool to generate bogus ORC data.

       - Prevent unwinder warnings when dumping the stack of a
         non-current task as there is no way to be sure about the
         validity because the dumped stack can be a moving target.

       - Make the ORC unwinder behave the same way as the frame pointer
         unwinder when dumping an inactive tasks stack and do not skip
         the first frame.

       - Prevent ORC unwinding before ORC data has been initialized

       - Immediately terminate unwinding when a unknown ORC entry type
         is found.

       - Prevent premature stop of the unwinder caused by IRET frames.

       - Fix another infinite loop in objtool caused by a negative
         offset which was not catched.

       - Address a few build warnings in the ORC unwinder and add
         missing static/ro_after_init annotations"

* tag 'x86-urgent-2020-05-10' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/unwind/orc: Move ORC sorting variables under !CONFIG_MODULES
  x86/apic: Move TSC deadline timer debug printk
  ftrace/x86: Fix trace event registration for syscalls without arguments
  x86/mm/cpa: Flush direct map alias during cpa
  objtool: Fix infinite loop in for_offset_range()
  x86/unwind/orc: Fix premature unwind stoppage due to IRET frames
  x86/unwind/orc: Fix error path for bad ORC entry type
  x86/unwind/orc: Prevent unwinding before ORC initialization
  x86/unwind/orc: Don't skip the first frame for inactive tasks
  x86/unwind: Prevent false warnings for non-current tasks
  x86/unwind/orc: Convert global variables to static
  x86/entry/64: Fix unwind hints in rewind_stack_do_exit()
  x86/entry/64: Fix unwind hints in __switch_to_asm()
  x86/entry/64: Fix unwind hints in kernel exit path
  x86/entry/64: Fix unwind hints in register clearing code
  objtool: Fix stack offset tracking for indirect CFAs
      c14cab26
    • Linus Torvalds's avatar
      Merge tag 'objtool-urgent-2020-05-10' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip · 8b000832
      Linus Torvalds authored 
      Pull objtool fix from Thomas Gleixner:
 "A single fix for objtool to prevent an infinite loop in the
  jump table search which can be triggered when building the
  kernel with '-ffunction-sections'"

* tag 'objtool-urgent-2020-05-10' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  objtool: Fix infinite loop in find_jump_table()
      8b000832
    • Linus Torvalds's avatar
      Merge tag 'locking-urgent-2020-05-10' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip · bd2049f8
      Linus Torvalds authored 
      Pull locking fix from Thomas Gleixner:
 "A single fix for the fallout of the recent futex uacess rework.

  With those changes GCC9 fails to analyze arch_futex_atomic_op_inuser()
  correctly and emits a 'maybe unitialized' warning. While we usually
  ignore compiler stupidity the conditional store is pointless anyway
  because the correct case has to store. For the fault case the extra
  store does no harm"

* tag 'locking-urgent-2020-05-10' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  ARM: futex: Address build warning
      bd2049f8
    • Linus Torvalds's avatar
      Merge tag 'iommu-fixes-v5.7-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/joro/iommu · 27d2dcb1
      Linus Torvalds authored 
      Pull iommu fixes from Joerg Roedel:

 - Race condition fixes for the AMD IOMMU driver.

   These are five patches fixing two race conditions around
   increase_address_space(). The first race condition was around the
   non-atomic update of the domain page-table root pointer and the
   variable containing the page-table depth (called mode). This is fixed
   now be merging page-table root and mode into one 64-bit field which
   is read/written atomically.

   The second race condition was around updating the page-table root
   pointer and making it public before the hardware caches were flushed.
   This could cause addresses to be mapped and returned to drivers which
   are not reachable by IOMMU hardware yet, causing IO page-faults. This
   is fixed too by adding the necessary flushes before a new page-table
   root is published.

   Related to the race condition fixes these patches also add a missing
   domain_flush_complete() barrier to update_domain() and a fix to bail
   out of the loop which tries to increase the address space when the
   call to increase_address_space() fails.

   Qian was able to trigger the race conditions under high load and
   memory pressure within a few days of testing. He confirmed that he
   has seen no issues anymore with the fixes included here.

 - Fix for a list-handling bug in the VirtIO IOMMU driver.

* tag 'iommu-fixes-v5.7-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/joro/iommu:
  iommu/virtio: Reverse arguments to list_add
  iommu/amd: Do not flush Device Table in iommu_map_page()
  iommu/amd: Update Device Table in increase_address_space()
  iommu/amd: Call domain_flush_complete() in update_domain()
  iommu/amd: Do not loop forever when trying to increase address space
  iommu/amd: Fix race in increase_address_space()/fetch_pte()
      27d2dcb1
    • Linus Torvalds's avatar
      Merge tag 'block-5.7-2020-05-09' of git://git.kernel.dk/linux-block · 0a85ed6e
      Linus Torvalds authored 
      Pull block fixes from Jens Axboe:

 - a small series fixing a use-after-free of bdi name (Christoph,Yufen)

 - NVMe fix for a regression with the smaller CQ update (Alexey)

 - NVMe fix for a hang at namespace scanning error recovery (Sagi)

 - fix race with blk-iocost iocg->abs_vdebt updates (Tejun)

* tag 'block-5.7-2020-05-09' of git://git.kernel.dk/linux-block:
  nvme: fix possible hang when ns scanning fails during error recovery
  nvme-pci: fix "slimmer CQ head update"
  bdi: add a ->dev_name field to struct backing_dev_info
  bdi: use bdi_dev_name() to get device name
  bdi: move bdi_dev_name out of line
  vboxsf: don't use the source name in the bdi name
  iocost: protect iocg->abs_vdebt with iocg->waitq.lock
      0a85ed6e
    • Linus Torvalds's avatar
      gcc-10: mark more functions __init to avoid section mismatch warnings · e99332e7
      Linus Torvalds authored 
      It seems that for whatever reason, gcc-10 ends up not inlining a couple
of functions that used to be inlined before.  Even if they only have one
single callsite - it looks like gcc may have decided that the code was
unlikely, and not worth inlining.

The code generation difference is harmless, but caused a few new section
mismatch errors, since the (now no longer inlined) function wasn't in
the __init section, but called other init functions:

   Section mismatch in reference from the function kexec_free_initrd() to the function .init.text:free_initrd_mem()
   Section mismatch in reference from the function tpm2_calc_event_log_size() to the function .init.text:early_memremap()
   Section mismatch in reference from the function tpm2_calc_event_log_size() to the function .init.text:early_memunmap()

So add the appropriate __init annotation to make modpost not complain.
In both cases there were trivially just a single callsite from another
__init function.
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      e99332e7
  9. 09 May, 2020 12 commits
    • Linus Torvalds's avatar
      Merge tag 'riscv-for-linus-5.7-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux · 2e28f3b1
      Linus Torvalds authored 
      Pull RISC-V fixes from Palmer Dabbelt:
 "A smattering of fixes and cleanups:

   - Dead code removal.

   - Exporting riscv_cpuid_to_hartid_mask for modules.

   - Per-CPU tracking of ISA features.

   - Setting max_pfn correctly when probing memory.

   - Adding a note to the VDSO so glibc can check the kernel's version
     without a uname().

   - A fix to force the bootloader to initialize the boot spin tables,
     which still get used as a fallback when SBI-0.1 is enabled"

* tag 'riscv-for-linus-5.7-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux:
  RISC-V: Remove unused code from STRICT_KERNEL_RWX
  riscv: force __cpu_up_ variables to put in data section
  riscv: add Linux note to vdso
  riscv: set max_pfn to the PFN of the last page
  RISC-V: Remove N-extension related defines
  RISC-V: Add bitmap reprensenting ISA features common across CPUs
  RISC-V: Export riscv_cpuid_to_hartid_mask() API
      2e28f3b1
    • Linus Torvalds's avatar
      gcc-10: avoid shadowing standard library 'free()' in crypto · 1a263ae6
      Linus Torvalds authored 
      gcc-10 has started warning about conflicting types for a few new
built-in functions, particularly 'free()'.

This results in warnings like:

   crypto/xts.c:325:13: warning: conflicting types for built-in function ‘free’; expected ‘void(void *)’ [-Wbuiltin-declaration-mismatch]

because the crypto layer had its local freeing functions called
'free()'.

Gcc-10 is in the wrong here, since that function is marked 'static', and
thus there is no chance of confusion with any standard library function
namespace.

But the simplest thing to do is to just use a different name here, and
avoid this gcc mis-feature.

[ Side note: gcc knowing about 'free()' is in itself not the
  mis-feature: the semantics of 'free()' are special enough that a
  compiler can validly do special things when seeing it.

  So the mis-feature here is that gcc thinks that 'free()' is some
  restricted name, and you can't shadow it as a local static function.

  Making the special 'free()' semantics be a function attribute rather
  than tied to the name would be the much better model ]
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      1a263ae6
    • Linus Torvalds's avatar
      gcc-10: disable 'restrict' warning for now · adc71920
      Linus Torvalds authored 
      gcc-10 now warns about passing aliasing pointers to functions that take
restricted pointers.

That's actually a great warning, and if we ever start using 'restrict'
in the kernel, it might be quite useful.  But right now we don't, and it
turns out that the only thing this warns about is an idiom where we have
declared a few functions to be "printf-like" (which seems to make gcc
pick up the restricted pointer thing), and then we print to the same
buffer that we also use as an input.

And people do that as an odd concatenation pattern, with code like this:

    #define sysfs_show_gen_prop(buffer, fmt, ...) \
        snprintf(buffer, PAGE_SIZE, "%s"fmt, buffer, __VA_ARGS__)

where we have 'buffer' as both the destination of the final result, and
as the initial argument.

Yes, it's a bit questionable.  And outside of the kernel, people do have
standard declarations like

    int snprintf( char *restrict buffer, size_t bufsz,
                  const char *restrict format, ... );

where that output buffer is marked as a restrict pointer that cannot
alias with any other arguments.

But in the context of the kernel, that 'use snprintf() to concatenate to
the end result' does work, and the pattern shows up in multiple places.
And we have not marked our own version of snprintf() as taking restrict
pointers, so the warning is incorrect for now, and gcc picks it up on
its own.

If we do start using 'restrict' in the kernel (and it might be a good
idea if people find places where it matters), we'll need to figure out
how to avoid this issue for snprintf and friends.  But in the meantime,
this warning is not useful.
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      adc71920
    • Linus Torvalds's avatar
      gcc-10: disable 'stringop-overflow' warning for now · 5a76021c
      Linus Torvalds authored 
      This is the final array bounds warning removal for gcc-10 for now.

Again, the warning is good, and we should re-enable all these warnings
when we have converted all the legacy array declaration cases to
flexible arrays. But in the meantime, it's just noise.
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      5a76021c
    • Sagi Grimberg's avatar
      nvme: fix possible hang when ns scanning fails during error recovery · 59c7c3ca
      Sagi Grimberg authored 
      When the controller is reconnecting, the host fails I/O and admin
commands as the host cannot reach the controller. ns scanning may
revalidate namespaces during that period and it is wrong to remove
namespaces due to these failures as we may hang (see 205da243).

One command that may fail is nvme_identify_ns_descs. Since we return
success due to having ns identify descriptor list optional, we continue
to compare ns identifiers in nvme_revalidate_disk, obviously fail and
return -ENODEV to nvme_validate_ns, which will remove the namespace.

Exactly what we don't want to happen.

Fixes: 22802bf7 ("nvme: Namepace identification descriptor list is optional")
Tested-by: default avatarAnton Eidelman <anton@lightbitslabs.com>
Signed-off-by: default avatarSagi Grimberg <sagi@grimberg.me>
Reviewed-by: default avatarKeith Busch <kbusch@kernel.org>
Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
      59c7c3ca
    • Alexey Dobriyan's avatar
      nvme-pci: fix "slimmer CQ head update" · a8de6639
      Alexey Dobriyan authored 
      Pre-incrementing ->cq_head can't be done in memory because OOB value
can be observed by another context.

This devalues space savings compared to original code :-\

	$ ./scripts/bloat-o-meter ../vmlinux-000 ../obj/vmlinux
	add/remove: 0/0 grow/shrink: 0/4 up/down: 0/-32 (-32)
	Function                                     old     new   delta
	nvme_poll_irqdisable                         464     456      -8
	nvme_poll                                    455     447      -8
	nvme_irq                                     388     380      -8
	nvme_dev_disable                             955     947      -8

But the code is minimal now: one read for head, one read for q_depth,
one increment, one comparison, single instruction phase bit update and
one write for new head.
Signed-off-by: default avatarAlexey Dobriyan <adobriyan@gmail.com>
Reported-by: default avatarJohn Garry <john.garry@huawei.com>
Tested-by: default avatarJohn Garry <john.garry@huawei.com>
Fixes: e2a366a4 ("nvme-pci: slimmer CQ head update")
Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
      a8de6639
    • Christoph Hellwig's avatar
      bdi: add a ->dev_name field to struct backing_dev_info · 6bd87eec
      Christoph Hellwig authored 
      Cache a copy of the name for the life time of the backing_dev_info
structure so that we can reference it even after unregistering.

Fixes: 68f23b89 ("memcg: fix a crash in wb_workfn when a device disappears")
Reported-by: default avatarYufen Yu <yuyufen@huawei.com>
Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Reviewed-by: default avatarJan Kara <jack@suse.cz>
Reviewed-by: default avatarBart Van Assche <bvanassche@acm.org>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
      6bd87eec
    • Yufen Yu's avatar
      bdi: use bdi_dev_name() to get device name · d51cfc53
      Yufen Yu authored 
      Use the common interface bdi_dev_name() to get device name.
Signed-off-by: default avatarYufen Yu <yuyufen@huawei.com>
Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Reviewed-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: default avatarJan Kara <jack@suse.cz>
Reviewed-by: default avatarBart Van Assche <bvanassche@acm.org>

Add missing <linux/backing-dev.h> include BFQ
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
      d51cfc53
    • Linus Torvalds's avatar
      gcc-10: disable 'array-bounds' warning for now · 44720996
      Linus Torvalds authored 
      This is another fine warning, related to the 'zero-length-bounds' one,
but hitting the same historical code in the kernel.

Because C didn't historically support flexible array members, we have
code that instead uses a one-sized array, the same way we have cases of
zero-sized arrays.

The one-sized arrays come from either not wanting to use the gcc
zero-sized array extension, or from a slight convenience-feature, where
particularly for strings, the size of the structure now includes the
allocation for the final NUL character.

So with a "char name[1];" at the end of a structure, you can do things
like

       v = my_malloc(sizeof(struct vendor) + strlen(name));

and avoid the "+1" for the terminator.

Yes, the modern way to do that is with a flexible array, and using
'offsetof()' instead of 'sizeof()', and adding the "+1" by hand.  That
also technically gets the size "more correct" in that it avoids any
alignment (and thus padding) issues, but this is another long-term
cleanup thing that will not happen for 5.7.

So disable the warning for now, even though it's potentially quite
useful.  Having a slew of warnings that then hide more urgent new issues
is not an improvement.
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      44720996
    • Linus Torvalds's avatar
      gcc-10: disable 'zero-length-bounds' warning for now · 5c45de21
      Linus Torvalds authored 
      This is a fine warning, but we still have a number of zero-length arrays
in the kernel that come from the traditional gcc extension.  Yes, they
are getting converted to flexible arrays, but in the meantime the gcc-10
warning about zero-length bounds is very verbose, and is hiding other
issues.

I missed one actual build failure because it was hidden among hundreds
of lines of warning.  Thankfully I caught it on the second go before
pushing things out, but it convinced me that I really need to disable
the new warnings for now.

We'll hopefully be all done with our conversion to flexible arrays in
the not too distant future, and we can then re-enable this warning.
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      5c45de21
    • Linus Torvalds's avatar
      Stop the ad-hoc games with -Wno-maybe-initialized · 78a5255f
      Linus Torvalds authored 
      We have some rather random rules about when we accept the
"maybe-initialized" warnings, and when we don't.

For example, we consider it unreliable for gcc versions < 4.9, but also
if -O3 is enabled, or if optimizing for size.  And then various kernel
config options disabled it, because they know that they trigger that
warning by confusing gcc sufficiently (ie PROFILE_ALL_BRANCHES).

And now gcc-10 seems to be introducing a lot of those warnings too, so
it falls under the same heading as 4.9 did.

At the same time, we have a very straightforward way to _enable_ that
warning when wanted: use "W=2" to enable more warnings.

So stop playing these ad-hoc games, and just disable that warning by
default, with the known and straight-forward "if you want to work on the
extra compiler warnings, use W=123".

Would it be great to have code that is always so obvious that it never
confuses the compiler whether a variable is used initialized or not?
Yes, it would.  In a perfect world, the compilers would be smarter, and
our source code would be simpler.

That's currently not the world we live in, though.
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      78a5255f
    • Linus Torvalds's avatar
      Merge tag 'io_uring-5.7-2020-05-08' of git://git.kernel.dk/linux-block · 1d3962ae
      Linus Torvalds authored 
      Pull io_uring fixes from Jens Axboe:

 - Fix finish_wait() balancing in file cancelation (Xiaoguang)

 - Ensure early cleanup of resources in ring map failure (Xiaoguang)

 - Ensure IORING_OP_SLICE does the right file mode checks (Pavel)

 - Remove file opening from openat/openat2/statx, it's not needed and
   messes with O_PATH

* tag 'io_uring-5.7-2020-05-08' of git://git.kernel.dk/linux-block:
  io_uring: don't use 'fd' for openat/openat2/statx
  splice: move f_mode checks to do_{splice,tee}()
  io_uring: handle -EFAULT properly in io_uring_setup()
  io_uring: fix mismatched finish_wait() calls in io_uring_cancel_files()
      1d3962ae
  11. 08 May, 2020 2 commits
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