Duplicating the can_sleep value in GPIO device will allow us to not
needlessly dereference the chip pointer in several places and reduce the
number of SRCU read-only critical sections.
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

We don't need to check the gdev pointer in struct gpio_desc - it's
always assigned and never cleared. It's also pointless to check
gdev->chip before we actually serialize access to it.
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

Checking desc->gdev->chip for NULL without holding it in place with some
serializing mechanism is pointless. Remove this check. Also don't check
desc->gdev for NULL as it can never happen. We'll be protecting
gdev->chip with SRCU soon but we will provide a dedicated, automatic
class for that.
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

We don't need to dereference gdev->chip in gpiochip_setup_dev() as at
the time it's called, the label in the associated struct gpio_device is
already set.
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

Don't dereference gdev->chip if the same information can be obtained
from struct gpio_device.
Suggested-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

The variable holding the number of GPIO lines is duplicated in GPIO
device so read it instead of unnecessarily dereferencing the chip
pointer.
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

gpio_device_get_desc() is the safer alternative to gpiochip_get_desc().
As we don't really need to dereference the chip pointer to retrieve the
descriptors in character device code, let's use it.
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

We're working towards protecting the chip pointer in struct gpio_device
with SRCU. In order to use it in sysfs callbacks we must pass the pointer
to the GPIO device that wraps the chip instead of the address of the
chip itself as the user data.
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

Checking the gdev->mockdev pointer for NULL must be part of the critical
section.
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

The GPIO chip pointer is unused. Let's remove it.
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

We now removed the gpio_lock spinlock and modified the places
previously protected by it to handle desc->flags access in a consistent
way. Let's improve other places that were previously unprotected by
reading the flags field of gpio_desc once and using the stored value for
logic consistency. If we need to modify the field, let's also write it
back once with a consistent value resulting from the function's logic.
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

The "multi-function" gpio_lock is pretty much useless with how it's used
in GPIOLIB currently. Because many GPIO API calls can be called from all
contexts but may also call into sleeping driver callbacks, there are
many places with utterly broken workarounds like yielding the lock to
call a possibly sleeping function and then re-acquiring it again without
taking into account that the protected state may have changed.

It was also used to protect several unrelated things: like individual
descriptors AND the GPIO device list. We now serialize access to these
two with SRCU and so can finally remove the spinlock.

There is of course the question of consistency of lockless access to
GPIO descriptors. Because we only support exclusive access to GPIOs
(officially anyway, I'm looking at you broken
GPIOD_FLAGS_BIT_NONEXCLUSIVE bit...) and the API contract with providers
does not guarantee serialization, it's enough to ensure we cannot
accidentally dereference an invalid pointer and that the state we present
to both users and providers remains consistent. To achieve that: read the
flags field atomically except for a few special cases. Read their current
value before executing callback code and use this value for any subsequent
logic. Modifying the flags depends on the particular use-case and can
differ. For instance: when requesting a GPIO, we need to set the
REQUESTED bit immediately so that the next user trying to request the
same line sees -EBUSY.

While at it: the allocations that used GFP_ATOMIC until this point can
now switch to GFP_KERNEL.
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

With the list of GPIO devices now protected with SRCU we can use
gpio_device_find() to traverse it from sysfs.
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

In order to ensure that the label is not freed while it's being
accessed, let's protect it with SRCU and synchronize it everytime it's
changed.

Let's modify desc_set_label() to manage the memory used for the label as
it can only be freed once synchronize_srcu() returns.
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

Extend the GPIO descriptor with an SRCU structure in order to serialize
the access to the label. Initialize and clean it up where applicable.
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

We will soon serialize access to the descriptor label using SRCU. The
write-side of the protection will require calling synchronize_srcu()
which must not be called from atomic context. We have two irq helpers:
gpiochip_lock_as_irq() and gpiochip_unlock_as_irq() that set the label
if the GPIO is not requested but is being used as interrupt. They are
called with a spinlock held from the interrupt subsystem.

They must not do it if we are to use SRCU so instead let's move the
special corner case to a dedicated getter.

Don't actually set the label to "interrupt" in the above case but rather
use the newly added gpiod_get_label() helper to hide the logic that
atomically checks the descriptor flags and returns the address of a
static "interrupt" string.
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

We will soon serialize access to the descriptor label using SRCU. The
write-side of the protection will require calling synchronize_srcu()
which must not be called from atomic context. We have two irq helpers:
gpiochip_lock_as_irq() and gpiochip_unlock_as_irq() that set the label
if the GPIO is not requested but is being used as interrupt. They are
called with a spinlock held from the interrupt subsystem.

They must not do it if we are to use SRCU so instead let's move the
special corner case to a dedicated getter.

First: let's implement and use the getter where it's applicable.
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

The general rule of the kernel is to not provide symbols that have no
users upstream. Let's remove logging helpers that are not used anywhere.

This will save us work later when we'll be modifying them to use the
upcoming SRCU infrastructure.
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

The device nodes representing GPIO hogs cannot be deleted without
unregistering the GPIO chip so there's no need to serialize their access.
However we must ensure that users can get the right address so write and
read it atomically.
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

We're working towards removing the "multi-function" GPIO spinlock that's
implemented terribly wrong. We tried using an RW-semaphore to protect
the list of GPIO devices but it turned out that we still have old code
using legacy GPIO calls that need to translate the global GPIO number to
the address of the associated descriptor and - to that end - traverse
the list while holding the lock. If we change the spinlock to a sleeping
lock then we'll end up with "scheduling while atomic" bugs.

Let's allow lockless traversal of the list using SRCU and only use the
mutex when modyfing the list.

While at it: let's protect the period between when we start the lookup
and when we finally request the descriptor (increasing the reference
count of the GPIO device) with the SRCU read lock.
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

The match function used in gpio_device_find() should not modify the
contents of passed opaque pointer, because such modification would not
be necessary for actual matching and it could lead to quite unreadable,
spaghetti code.
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
[Bartosz: fix coding style in header]
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>

Linux 6.8-rc4

Pulling this for a bugfix upstream with which the gpio/for-next branch
conflicts.

Pull timer fix from Borislav Petkov:

 - Make sure a warning is issued when a hrtimer gets queued after the
   timers have been migrated on the CPU down path and thus said timer
   will get ignored

* tag 'timers_urgent_for_v6.8_rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  hrtimer: Report offline hrtimer enqueue

Pull x86 fixes from Borislav Petkov:

 - Correct the minimum CPU family for Transmeta Crusoe in Kconfig so
   that such hw can boot again

 - Do not take into accout XSTATE buffer size info supplied by userspace
   when constructing a sigreturn frame

 - Switch get_/put_user* to EX_TYPE_UACCESS exception handling when an
   MCE is encountered so that it can be properly recovered from instead
   of simply panicking

* tag 'x86_urgent_for_v6.8_rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/Kconfig: Transmeta Crusoe is CPU family 5, not 6
  x86/fpu: Stop relying on userspace for info to fault in xsave buffer
  x86/lib: Revert to _ASM_EXTABLE_UA() for {get,put}_user() fixups

Merge tag 'mm-hotfixes-stable-2024-02-10-11-16' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Pull misc fixes from Andrew Morton:
 "21 hotfixes. 12 are cc:stable and the remainder pertain to post-6.7
  issues or aren't considered to be needed in earlier kernel versions"

* tag 'mm-hotfixes-stable-2024-02-10-11-16' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (21 commits)
  nilfs2: fix potential bug in end_buffer_async_write
  mm/damon/sysfs-schemes: fix wrong DAMOS tried regions update timeout setup
  nilfs2: fix hang in nilfs_lookup_dirty_data_buffers()
  MAINTAINERS: Leo Yan has moved
  mm/zswap: don't return LRU_SKIP if we have dropped lru lock
  fs,hugetlb: fix NULL pointer dereference in hugetlbs_fill_super
  mailmap: switch email address for John Moon
  mm: zswap: fix objcg use-after-free in entry destruction
  mm/madvise: don't forget to leave lazy MMU mode in madvise_cold_or_pageout_pte_range()
  arch/arm/mm: fix major fault accounting when retrying under per-VMA lock
  selftests: core: include linux/close_range.h for CLOSE_RANGE_* macros
  mm/memory-failure: fix crash in split_huge_page_to_list from soft_offline_page
  mm: memcg: optimize parent iteration in memcg_rstat_updated()
  nilfs2: fix data corruption in dsync block recovery for small block sizes
  mm/userfaultfd: UFFDIO_MOVE implementation should use ptep_get()
  exit: wait_task_zombie: kill the no longer necessary spin_lock_irq(siglock)
  fs/proc: do_task_stat: use sig->stats_lock to gather the threads/children stats
  fs/proc: do_task_stat: move thread_group_cputime_adjusted() outside of lock_task_sighand()
  getrusage: use sig->stats_lock rather than lock_task_sighand()
  getrusage: move thread_group_cputime_adjusted() outside of lock_task_sighand()
  ...

Pull block fixes from Jens Axboe:

 - NVMe pull request via Keith:
     - Update a potentially stale firmware attribute (Maurizio)
     - Fixes for the recent verbose error logging (Keith, Chaitanya)
     - Protection information payload size fix for passthrough (Francis)

 - Fix for a queue freezing issue in virtblk (Yi)

 - blk-iocost underflow fix (Tejun)

 - blk-wbt task detection fix (Jan)

* tag 'block-6.8-2024-02-10' of git://git.kernel.dk/linux:
  virtio-blk: Ensure no requests in virtqueues before deleting vqs.
  blk-iocost: Fix an UBSAN shift-out-of-bounds warning
  nvme: use ns->head->pi_size instead of t10_pi_tuple structure size
  nvme-core: fix comment to reflect right functions
  nvme: move passthrough logging attribute to head
  blk-wbt: Fix detection of dirty-throttled tasks
  nvme-host: fix the updating of the firmware version

Merge tag 'firewire-fixes-6.8-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/ieee1394/linux1394

Pull firewire fix from Takashi Sakamoto:
 "A change to accelerate the device detection step in some cases.

  In the self-identification step after bus-reset, all nodes in the same
  bus broadcast selfID packet including the value of gap count. The
  value is related to the cable hops between nodes, and used to
  calculate the subaction gap and the arbitration reset gap.

  When each node has the different value of the gap count, the
  asynchronous communication between them is unreliable, since an
  asynchronous transaction could be interrupted by another asynchronous
  transaction before completion. The gap count inconsistency can be
  resolved by several ways; e.g. the transfer of PHY configuration
  packet and generation of bus-reset.

  The current implementation of firewire stack can correctly detect the
  gap count inconsistency, however the recovery action from the
  inconsistency tends to be delayed after reading configuration ROM of
  root node. This results in the long time to probe devices in some
  combinations of hardware.

  Here the stack is changed to schedule the action as soon as possible"

* tag 'firewire-fixes-6.8-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/ieee1394/linux1394:
  firewire: core: send bus reset promptly on gap count error

Pull smb server fixes from Steve French:
 "Two ksmbd server fixes:

   - memory leak fix

   - a minor kernel-doc fix"

* tag '6.8-rc3-ksmbd-server-fixes' of git://git.samba.org/ksmbd:
  ksmbd: free aux buffer if ksmbd_iov_pin_rsp_read fails
  ksmbd: Add kernel-doc for ksmbd_extract_sharename() function

Pull SCSI fixes from James Bottomley:
 "Three small driver fixes and one core fix.

  The core fix being a fixup to the one in the last pull request which
  didn't entirely move checking of scsi_host_busy() out from under the
  host lock"

* tag 'scsi-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi:
  scsi: ufs: core: Remove the ufshcd_release() in ufshcd_err_handling_prepare()
  scsi: ufs: core: Fix shift issue in ufshcd_clear_cmd()
  scsi: lpfc: Use unsigned type for num_sge
  scsi: core: Move scsi_host_busy() out of host lock if it is for per-command

Pull smb client fixes from Steve French:

 - reconnect fix

 - multichannel channel selection fix

 - minor mount warning fix

 - reparse point fix

 - null pointer check improvement

* tag '6.8-rc3-smb3-client-fixes' of git://git.samba.org/sfrench/cifs-2.6:
  smb3: clarify mount warning
  cifs: handle cases where multiple sessions share connection
  cifs: change tcon status when need_reconnect is set on it
  smb: client: set correct d_type for reparse points under DFS mounts
  smb3: add missing null server pointer check

Pull ceph fixes from Ilya Dryomov:
 "Some fscrypt-related fixups (sparse reads are used only for encrypted
  files) and two cap handling fixes from Xiubo and Rishabh"

* tag 'ceph-for-6.8-rc4' of https://github.com/ceph/ceph-client:
  ceph: always check dir caps asynchronously
  ceph: prevent use-after-free in encode_cap_msg()
  ceph: always set initial i_blkbits to CEPH_FSCRYPT_BLOCK_SHIFT
  libceph: just wait for more data to be available on the socket
  libceph: rename read_sparse_msg_*() to read_partial_sparse_msg_*()
  libceph: fail sparse-read if the data length doesn't match

Pull ntfs3 fixes from Konstantin Komarov:
 "Fixed:
   - size update for compressed file
   - some logic errors, overflows
   - memory leak
   - some code was refactored

  Added:
   - implement super_operations::shutdown

  Improved:
   - alternative boot processing
   - reduced stack usage"

* tag 'ntfs3_for_6.8' of https://github.com/Paragon-Software-Group/linux-ntfs3: (28 commits)
  fs/ntfs3: Slightly simplify ntfs_inode_printk()
  fs/ntfs3: Add ioctl operation for directories (FITRIM)
  fs/ntfs3: Fix oob in ntfs_listxattr
  fs/ntfs3: Fix an NULL dereference bug
  fs/ntfs3: Update inode->i_size after success write into compressed file
  fs/ntfs3: Fixed overflow check in mi_enum_attr()
  fs/ntfs3: Correct function is_rst_area_valid
  fs/ntfs3: Use i_size_read and i_size_write
  fs/ntfs3: Prevent generic message "attempt to access beyond end of device"
  fs/ntfs3: use non-movable memory for ntfs3 MFT buffer cache
  fs/ntfs3: Use kvfree to free memory allocated by kvmalloc
  fs/ntfs3: Disable ATTR_LIST_ENTRY size check
  fs/ntfs3: Fix c/mtime typo
  fs/ntfs3: Add NULL ptr dereference checking at the end of attr_allocate_frame()
  fs/ntfs3: Add and fix comments
  fs/ntfs3: ntfs3_forced_shutdown use int instead of bool
  fs/ntfs3: Implement super_operations::shutdown
  fs/ntfs3: Drop suid and sgid bits as a part of fpunch
  fs/ntfs3: Add file_modified
  fs/ntfs3: Correct use bh_read
  ...

We've had issues with gcc and 'asm goto' before, and we created a
'asm_volatile_goto()' macro for that in the past: see commits
3f0116c3 ("compiler/gcc4: Add quirk for 'asm goto' miscompilation
bug") and a9f18034 ("compiler/gcc4: Make quirk for
asm_volatile_goto() unconditional").

Then, much later, we ended up removing the workaround in commit
43c249ea ("compiler-gcc.h: remove ancient workaround for gcc PR
58670") because we no longer supported building the kernel with the
affected gcc versions, but we left the macro uses around.

Now, Sean Christopherson reports a new version of a very similar
problem, which is fixed by re-applying that ancient workaround.  But the
problem in question is limited to only the 'asm goto with outputs'
cases, so instead of re-introducing the old workaround as-is, let's
rename and limit the workaround to just that much less common case.

It looks like there are at least two separate issues that all hit in
this area:

 (a) some versions of gcc don't mark the asm goto as 'volatile' when it
     has outputs:

        https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98619
        https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110420

     which is easy to work around by just adding the 'volatile' by hand.

 (b) Internal compiler errors:

        https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110422

     which are worked around by adding the extra empty 'asm' as a
     barrier, as in the original workaround.

but the problem Sean sees may be a third thing since it involves bad
code generation (not an ICE) even with the manually added 'volatile'.

but the same old workaround works for this case, even if this feels a
bit like voodoo programming and may only be hiding the issue.
Reported-and-tested-by: Sean Christopherson <seanjc@google.com>
Link: https://lore.kernel.org/all/20240208220604.140859-1-seanjc@google.com/
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Uros Bizjak <ubizjak@gmail.com>
Cc: Jakub Jelinek <jakub@redhat.com>
Cc: Andrew Pinski <quic_apinski@quicinc.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

When a user tries to use the "sec=krb5p" mount parameter to encrypt
data on connection to a server (when authenticating with Kerberos), we
indicate that it is not supported, but do not note the equivalent
recommended mount parameter ("sec=krb5,seal") which turns on encryption
for that mount (and uses Kerberos for auth).  Update the warning message.
Reviewed-by: Shyam Prasad N <sprasad@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>

Based on our implementation of multichannel, it is entirely
possible that a server struct may not be found in any channel
of an SMB session.

In such cases, we should be prepared to move on and search for
the server struct in the next session.
Signed-off-by: Shyam Prasad N <sprasad@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>

When a tcon is marked for need_reconnect, the intention
is to have it reconnected.

This change adjusts tcon->status in cifs_tree_connect
when need_reconnect is set. Also, this change has a minor
correction in resetting need_reconnect on success. It makes
sure that it is done with tc_lock held.
Signed-off-by: Shyam Prasad N <sprasad@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>

Pull RISC-V fixes from Palmer Dabbelt:

 - fix missing TLB flush during early boot on SPARSEMEM_VMEMMAP
   configurations

 - fixes to correctly implement the break-before-make behavior requried
   by the ISA for NAPOT mappings

 - fix a missing TLB flush on intermediate mapping changes

 - fix build warning about a missing declaration of overflow_stack

 - fix performace regression related to incorrect tracking of completed
   batch TLB flushes

* tag 'riscv-for-linus-6.8-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux:
  riscv: Fix arch_tlbbatch_flush() by clearing the batch cpumask
  riscv: declare overflow_stack as exported from traps.c
  riscv: Fix arch_hugetlb_migration_supported() for NAPOT
  riscv: Flush the tlb when a page directory is freed
  riscv: Fix hugetlb_mask_last_page() when NAPOT is enabled
  riscv: Fix set_huge_pte_at() for NAPOT mapping
  riscv: mm: execute local TLB flush after populating vmemmap

Pull tracing fixes from Steven Rostedt:

 - Fix broken direct trampolines being called when another callback is
   attached the same function.

   ARM 64 does not support FTRACE_WITH_REGS, and when it added direct
   trampoline calls from ftrace, it removed the "WITH_REGS" flag from
   the ftrace_ops for direct trampolines. This broke x86 as x86 requires
   direct trampolines to have WITH_REGS.

   This wasn't noticed because direct trampolines work as long as the
   function it is attached to is not shared with other callbacks (like
   the function tracer). When there are other callbacks, a helper
   trampoline is called, to call all the non direct callbacks and when
   it returns, the direct trampoline is called.

   For x86, the direct trampoline sets a flag in the regs field to tell
   the x86 specific code to call the direct trampoline. But this only
   works if the ftrace_ops had WITH_REGS set. ARM does things
   differently that does not require this. For now, set WITH_REGS if the
   arch supports WITH_REGS (which ARM does not), and this makes it work
   for both ARM64 and x86.

 - Fix wasted memory in the saved_cmdlines logic.

   The saved_cmdlines is a cache that maps PIDs to COMMs that tracing
   can use. Most trace events only save the PID in the event. The
   saved_cmdlines file lists PIDs to COMMs so that the tracing tools can
   show an actual name and not just a PID for each event. There's an
   array of PIDs that map to a small set of saved COMM strings. The
   array is set to PID_MAX_DEFAULT which is usually set to 32768. When a
   PID comes in, it will add itself to this array along with the index
   into the COMM array (note if the system allows more than
   PID_MAX_DEFAULT, this cache is similar to cache lines as an update of
   a PID that has the same PID_MAX_DEFAULT bits set will flush out
   another task with the same matching bits set).

   A while ago, the size of this cache was changed to be dynamic and the
   array was moved into a structure and created with kmalloc(). But this
   new structure had the size of 131104 bytes, or 0x20020 in hex. As
   kmalloc allocates in powers of two, it was actually allocating
   0x40000 bytes (262144) leaving 131040 bytes of wasted memory. The
   last element of this structure was a pointer to the COMM string array
   which defaulted to just saving 128 COMMs.

   By changing the last field of this structure to a variable length
   string, and just having it round up to fill the allocated memory, the
   default size of the saved COMM cache is now 8190. This not only uses
   the wasted space, but actually saves space by removing the extra
   allocation for the COMM names.

* tag 'trace-v6.8-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  tracing: Fix wasted memory in saved_cmdlines logic
  ftrace: Fix DIRECT_CALLS to use SAVE_REGS by default

Merge tag 'probes-fixes-v6.8-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace

Pull probes fixes from Masami Hiramatsu:

 - remove unnecessary initial values of kprobes local variables

 - probe-events parser bug fixes:

    - calculate the argument size and format string after setting type
      information from BTF, because BTF can change the size and format
      string.

    - show $comm parse error correctly instead of failing silently.

* tag 'probes-fixes-v6.8-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  kprobes: Remove unnecessary initial values of variables
  tracing/probes: Fix to set arg size and fmt after setting type from BTF
  tracing/probes: Fix to show a parse error for bad type for $comm