Maximilian reported that surface_serial_hub serdev tx does not work during
system suspend. During system suspend, runtime PM gets disabled in
__device_suspend_late(), and tx is unable to wake-up the serial core port
device that we use to check if tx is safe to start. Johan summarized the
regression noting that serdev tx no longer always works as earlier when the
serdev device is runtime PM active.

The serdev device and the serial core controller devices are siblings of
the serial port hardware device. The runtime PM usage count from serdev
device does not propagate to the serial core device siblings, it only
propagates to the parent.

In addition to the tx issue for suspend, testing for the serial core port
device can cause an unnecessary delay in enabling tx while waiting for the
serial core port device to wake-up. The serial core port device wake-up is
only needed to flush pending tx when the serial port hardware device was
in runtime PM suspended state.

To fix the regression, we need to check the runtime PM state of the parent
serial port hardware device for tx instead of the serial core port device.

As the serial port device drivers may or may not implement runtime PM, we
need to also add a check for pm_runtime_enabled().

Reported-by: Maximilian Luz <luzmaximilian@gmail.com>
Cc: stable <stable@kernel.org>
Fixes: 84a9582fd203 ("serial: core: Start managing serial controllers to enable runtime PM")
Signed-off-by: Tony Lindgren <tony@atomide.com>
Tested-by: Maximilian Luz <luzmaximilian@gmail.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20231005075644.25936-1-tony@atomide.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

We now get errors on system suspend if no_console_suspend is set as
reported by Thomas. The errors started with commit 20a41a62618d ("serial:
8250_omap: Use force_suspend and resume for system suspend").

Let's fix the issue by checking for console_suspend_enabled in the system
suspend and resume path.

Note that with this fix the checks for console_suspend_enabled in
omap8250_runtime_suspend() become useless. We now keep runtime PM usage
count for an attached kernel console starting with commit bedb404e91bb
("serial: 8250_port: Don't use power management for kernel console").

Fixes: 20a41a62618d ("serial: 8250_omap: Use force_suspend and resume for system suspend")
Cc: stable <stable@kernel.org>
Cc: Udit Kumar <u-kumar1@ti.com>
Reported-by: Thomas Richard <thomas.richard@bootlin.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>
Tested-by: Thomas Richard <thomas.richard@bootlin.com>
Reviewed-by: Dhruva Gole <d-gole@ti.com>
Link: https://lore.kernel.org/r/20230926061319.15140-1-tony@atomide.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Commit 44b27aec9d96 ("serial: core, 8250: set RS485 termination GPIO in
serial core") enabled support for RS485 termination GPIOs behind i2c
expanders by setting the GPIO outside of the critical section protected
by the port spinlock.  Access to the i2c expander may sleep, which
caused a splat with the port spinlock held.

Commit 7c7f9bc986e6 ("serial: Deassert Transmit Enable on probe in
driver-specific way") erroneously regressed that by spinlocking the
GPIO manipulation again.

Fix by moving uart_rs485_config() (the function manipulating the GPIO)
outside of the spinlocked section and acquiring the spinlock inside of
uart_rs485_config() for the invocation of ->rs485_config() only.

This gets us one step closer to pushing the spinlock down into the
->rs485_config() callbacks which actually need it.  (Some callbacks
do not want to be spinlocked because they perform sleepable register
accesses, see e.g. sc16is7xx_config_rs485().)

Stack trace for posterity:

 Voluntary context switch within RCU read-side critical section!
 WARNING: CPU: 0 PID: 56 at kernel/rcu/tree_plugin.h:318 rcu_note_context_switch
 Call trace:
 rcu_note_context_switch
 __schedule
 schedule
 schedule_timeout
 wait_for_completion_timeout
 bcm2835_i2c_xfer
 __i2c_transfer
 i2c_transfer
 i2c_transfer_buffer_flags
 regmap_i2c_write
 _regmap_raw_write_impl
 _regmap_bus_raw_write
 _regmap_write
 _regmap_update_bits
 regmap_update_bits_base
 pca953x_gpio_set_value
 gpiod_set_raw_value_commit
 gpiod_set_value_nocheck
 gpiod_set_value_cansleep
 uart_rs485_config
 uart_add_one_port
 pl011_register_port
 pl011_probe

Fixes: 7c7f9bc986e6 ("serial: Deassert Transmit Enable on probe in driver-specific way")
Suggested-by: Lino Sanfilippo <LinoSanfilippo@gmx.de>
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Cc: stable@vger.kernel.org # v6.1+
Link: https://lore.kernel.org/r/f3a35967c28b32f3c6432d0aa5936e6a9908282d.1695307688.git.lukas@wunner.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

This reverts commit 9b9c8195f3f0d74a826077fc1c01b9ee74907239.

The commit above is reverted as it did not solve the original issue.

gsm_cleanup_mux() tries to free up the virtual ttys by calling
gsm_dlci_release() for each available DLCI. There, dlci_put() is called to
decrease the reference counter for the DLCI via tty_port_put() which
finally calls gsm_dlci_free(). This already clears the pointer which is
being checked in gsm_cleanup_mux() before calling gsm_dlci_release().
Therefore, it is not necessary to clear this pointer in gsm_cleanup_mux()
as done in the reverted commit. The commit introduces a null pointer
dereference:
 <TASK>
 ? __die+0x1f/0x70
 ? page_fault_oops+0x156/0x420
 ? search_exception_tables+0x37/0x50
 ? fixup_exception+0x21/0x310
 ? exc_page_fault+0x69/0x150
 ? asm_exc_page_fault+0x26/0x30
 ? tty_port_put+0x19/0xa0
 gsmtty_cleanup+0x29/0x80 [n_gsm]
 release_one_tty+0x37/0xe0
 process_one_work+0x1e6/0x3e0
 worker_thread+0x4c/0x3d0
 ? __pfx_worker_thread+0x10/0x10
 kthread+0xe1/0x110
 ? __pfx_kthread+0x10/0x10
 ret_from_fork+0x2f/0x50
 ? __pfx_kthread+0x10/0x10
 ret_from_fork_asm+0x1b/0x30
 </TASK>

The actual issue is that nothing guards dlci_put() from being called
multiple times while the tty driver was triggered but did not yet finished
calling gsm_dlci_free().

Fixes: 9b9c8195f3f0 ("tty: n_gsm: fix UAF in gsm_cleanup_mux")
Cc: stable <stable@kernel.org>
Signed-off-by: Daniel Starke <daniel.starke@siemens.com>
Link: https://lore.kernel.org/r/20230914051507.3240-1-daniel.starke@siemens.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

In case the leaf driver wants to use IRQ polling (irq = 0) and
IIR register shows that an interrupt happened in the 8250 hardware
the IRQ data can be NULL. In such a case we need to skip the wake
event as we came to this path from the timer interrupt and quite
likely system is already awake.

Without this fix we have got an Oops:

    serial8250: ttyS0 at I/O 0x3f8 (irq = 0, base_baud = 115200) is a 16550A
    ...
    BUG: kernel NULL pointer dereference, address: 0000000000000010
    RIP: 0010:serial8250_handle_irq+0x7c/0x240
    Call Trace:
     ? serial8250_handle_irq+0x7c/0x240
     ? __pfx_serial8250_timeout+0x10/0x10

Fixes: 0ba9e3a13c6a ("serial: 8250: Add missing wakeup event reporting")
Cc: stable <stable@kernel.org>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Florian Fainelli <florian.fainelli@broadcom.com>
Link: https://lore.kernel.org/r/20230831222555.614426-1-andriy.shevchenko@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Pull tty/serial driver updates from Greg KH:
 "Here is the big set of tty and serial driver changes for 6.6-rc1.

  Lots of cleanups in here this cycle, and some driver updates. Short
  summary is:

   - Jiri's continued work to make the tty code and apis be a bit more
     sane with regards to modern kernel coding style and types

   - cpm_uart driver updates

   - n_gsm updates and fixes

   - meson driver updates

   - sc16is7xx driver updates

   - 8250 driver updates for different hardware types

   - qcom-geni driver fixes

   - tegra serial driver change

   - stm32 driver updates

   - synclink_gt driver cleanups

   - tty structure size reduction

  All of these have been in linux-next this week with no reported
  issues. The last bit of cleanups from Jiri and the tty structure size
  reduction came in last week, a bit late but as they were just style
  changes and size reductions, I figured they should get into this merge
  cycle so that others can work on top of them with no merge conflicts"

* tag 'tty-6.6-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty: (199 commits)
  tty: shrink the size of struct tty_struct by 40 bytes
  tty: n_tty: deduplicate copy code in n_tty_receive_buf_real_raw()
  tty: n_tty: extract ECHO_OP processing to a separate function
  tty: n_tty: unify counts to size_t
  tty: n_tty: use u8 for chars and flags
  tty: n_tty: simplify chars_in_buffer()
  tty: n_tty: remove unsigned char casts from character constants
  tty: n_tty: move newline handling to a separate function
  tty: n_tty: move canon handling to a separate function
  tty: n_tty: use MASK() for masking out size bits
  tty: n_tty: make n_tty_data::num_overrun unsigned
  tty: n_tty: use time_is_before_jiffies() in n_tty_receive_overrun()
  tty: n_tty: use 'num' for writes' counts
  tty: n_tty: use output character directly
  tty: n_tty: make flow of n_tty_receive_buf_common() a bool
  Revert "tty: serial: meson: Add a earlycon for the T7 SoC"
  Documentation: devices.txt: Fix minors for ttyCPM*
  Documentation: devices.txt: Remove ttySIOC*
  Documentation: devices.txt: Remove ttyIOC*
  serial: 8250_bcm7271: improve bcm7271 8250 port
  ...

Pull non-MM updates from Andrew Morton:

 - An extensive rework of kexec and crash Kconfig from Eric DeVolder
   ("refactor Kconfig to consolidate KEXEC and CRASH options")

 - kernel.h slimming work from Andy Shevchenko ("kernel.h: Split out a
   couple of macros to args.h")

 - gdb feature work from Kuan-Ying Lee ("Add GDB memory helper
   commands")

 - vsprintf inclusion rationalization from Andy Shevchenko
   ("lib/vsprintf: Rework header inclusions")

 - Switch the handling of kdump from a udev scheme to in-kernel
   handling, by Eric DeVolder ("crash: Kernel handling of CPU and memory
   hot un/plug")

 - Many singleton patches to various parts of the tree

* tag 'mm-nonmm-stable-2023-08-28-22-48' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (81 commits)
  document while_each_thread(), change first_tid() to use for_each_thread()
  drivers/char/mem.c: shrink character device's devlist[] array
  x86/crash: optimize CPU changes
  crash: change crash_prepare_elf64_headers() to for_each_possible_cpu()
  crash: hotplug support for kexec_load()
  x86/crash: add x86 crash hotplug support
  crash: memory and CPU hotplug sysfs attributes
  kexec: exclude elfcorehdr from the segment digest
  crash: add generic infrastructure for crash hotplug support
  crash: move a few code bits to setup support of crash hotplug
  kstrtox: consistently use _tolower()
  kill do_each_thread()
  nilfs2: fix WARNING in mark_buffer_dirty due to discarded buffer reuse
  scripts/bloat-o-meter: count weak symbol sizes
  treewide: drop CONFIG_EMBEDDED
  lockdep: fix static memory detection even more
  lib/vsprintf: declare no_hash_pointers in sprintf.h
  lib/vsprintf: split out sprintf() and friends
  kernel/fork: stop playing lockless games for exe_file replacement
  adfs: delete unused "union adfs_dirtail" definition
  ...

Pull MM updates from Andrew Morton:

 - Some swap cleanups from Ma Wupeng ("fix WARN_ON in
   add_to_avail_list")

 - Peter Xu has a series (mm/gup: Unify hugetlb, speed up thp") which
   reduces the special-case code for handling hugetlb pages in GUP. It
   also speeds up GUP handling of transparent hugepages.

 - Peng Zhang provides some maple tree speedups ("Optimize the fast path
   of mas_store()").

 - Sergey Senozhatsky has improved te performance of zsmalloc during
   compaction (zsmalloc: small compaction improvements").

 - Domenico Cerasuolo has developed additional selftest code for zswap
   ("selftests: cgroup: add zswap test program").

 - xu xin has doe some work on KSM's handling of zero pages. These
   changes are mainly to enable the user to better understand the
   effectiveness of KSM's treatment of zero pages ("ksm: support
   tracking KSM-placed zero-pages").

 - Jeff Xu has fixes the behaviour of memfd's
   MEMFD_NOEXEC_SCOPE_NOEXEC_ENFORCED sysctl ("mm/memfd: fix sysctl
   MEMFD_NOEXEC_SCOPE_NOEXEC_ENFORCED").

 - David Howells has fixed an fscache optimization ("mm, netfs, fscache:
   Stop read optimisation when folio removed from pagecache").

 - Axel Rasmussen has given userfaultfd the ability to simulate memory
   poisoning ("add UFFDIO_POISON to simulate memory poisoning with
   UFFD").

 - Miaohe Lin has contributed some routine maintenance work on the
   memory-failure code ("mm: memory-failure: remove unneeded PageHuge()
   check").

 - Peng Zhang has contributed some maintenance work on the maple tree
   code ("Improve the validation for maple tree and some cleanup").

 - Hugh Dickins has optimized the collapsing of shmem or file pages into
   THPs ("mm: free retracted page table by RCU").

 - Jiaqi Yan has a patch series which permits us to use the healthy
   subpages within a hardware poisoned huge page for general purposes
   ("Improve hugetlbfs read on HWPOISON hugepages").

 - Kemeng Shi has done some maintenance work on the pagetable-check code
   ("Remove unused parameters in page_table_check").

 - More folioification work from Matthew Wilcox ("More filesystem folio
   conversions for 6.6"), ("Followup folio conversions for zswap"). And
   from ZhangPeng ("Convert several functions in page_io.c to use a
   folio").

 - page_ext cleanups from Kemeng Shi ("minor cleanups for page_ext").

 - Baoquan He has converted some architectures to use the
   GENERIC_IOREMAP ioremap()/iounmap() code ("mm: ioremap: Convert
   architectures to take GENERIC_IOREMAP way").

 - Anshuman Khandual has optimized arm64 tlb shootdown ("arm64: support
   batched/deferred tlb shootdown during page reclamation/migration").

 - Better maple tree lockdep checking from Liam Howlett ("More strict
   maple tree lockdep"). Liam also developed some efficiency
   improvements ("Reduce preallocations for maple tree").

 - Cleanup and optimization to the secondary IOMMU TLB invalidation,
   from Alistair Popple ("Invalidate secondary IOMMU TLB on permission
   upgrade").

 - Ryan Roberts fixes some arm64 MM selftest issues ("selftests/mm fixes
   for arm64").

 - Kemeng Shi provides some maintenance work on the compaction code
   ("Two minor cleanups for compaction").

 - Some reduction in mmap_lock pressure from Matthew Wilcox ("Handle
   most file-backed faults under the VMA lock").

 - Aneesh Kumar contributes code to use the vmemmap optimization for DAX
   on ppc64, under some circumstances ("Add support for DAX vmemmap
   optimization for ppc64").

 - page-ext cleanups from Kemeng Shi ("add page_ext_data to get client
   data in page_ext"), ("minor cleanups to page_ext header").

 - Some zswap cleanups from Johannes Weiner ("mm: zswap: three
   cleanups").

 - kmsan cleanups from ZhangPeng ("minor cleanups for kmsan").

 - VMA handling cleanups from Kefeng Wang ("mm: convert to
   vma_is_initial_heap/stack()").

 - DAMON feature work from SeongJae Park ("mm/damon/sysfs-schemes:
   implement DAMOS tried total bytes file"), ("Extend DAMOS filters for
   address ranges and DAMON monitoring targets").

 - Compaction work from Kemeng Shi ("Fixes and cleanups to compaction").

 - Liam Howlett has improved the maple tree node replacement code
   ("maple_tree: Change replacement strategy").

 - ZhangPeng has a general code cleanup - use the K() macro more widely
   ("cleanup with helper macro K()").

 - Aneesh Kumar brings memmap-on-memory to ppc64 ("Add support for
   memmap on memory feature on ppc64").

 - pagealloc cleanups from Kemeng Shi ("Two minor cleanups for pcp list
   in page_alloc"), ("Two minor cleanups for get pageblock
   migratetype").

 - Vishal Moola introduces a memory descriptor for page table tracking,
   "struct ptdesc" ("Split ptdesc from struct page").

 - memfd selftest maintenance work from Aleksa Sarai ("memfd: cleanups
   for vm.memfd_noexec").

 - MM include file rationalization from Hugh Dickins ("arch: include
   asm/cacheflush.h in asm/hugetlb.h").

 - THP debug output fixes from Hugh Dickins ("mm,thp: fix sloppy text
   output").

 - kmemleak improvements from Xiaolei Wang ("mm/kmemleak: use
   object_cache instead of kmemleak_initialized").

 - More folio-related cleanups from Matthew Wilcox ("Remove _folio_dtor
   and _folio_order").

 - A VMA locking scalability improvement from Suren Baghdasaryan
   ("Per-VMA lock support for swap and userfaults").

 - pagetable handling cleanups from Matthew Wilcox ("New page table
   range API").

 - A batch of swap/thp cleanups from David Hildenbrand ("mm/swap: stop
   using page->private on tail pages for THP_SWAP + cleanups").

 - Cleanups and speedups to the hugetlb fault handling from Matthew
   Wilcox ("Change calling convention for ->huge_fault").

 - Matthew Wilcox has also done some maintenance work on the MM
   subsystem documentation ("Improve mm documentation").

* tag 'mm-stable-2023-08-28-18-26' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (489 commits)
  maple_tree: shrink struct maple_tree
  maple_tree: clean up mas_wr_append()
  secretmem: convert page_is_secretmem() to folio_is_secretmem()
  nios2: fix flush_dcache_page() for usage from irq context
  hugetlb: add documentation for vma_kernel_pagesize()
  mm: add orphaned kernel-doc to the rst files.
  mm: fix clean_record_shared_mapping_range kernel-doc
  mm: fix get_mctgt_type() kernel-doc
  mm: fix kernel-doc warning from tlb_flush_rmaps()
  mm: remove enum page_entry_size
  mm: allow ->huge_fault() to be called without the mmap_lock held
  mm: move PMD_ORDER to pgtable.h
  mm: remove checks for pte_index
  memcg: remove duplication detection for mem_cgroup_uncharge_swap
  mm/huge_memory: work on folio->swap instead of page->private when splitting folio
  mm/swap: inline folio_set_swap_entry() and folio_swap_entry()
  mm/swap: use dedicated entry for swap in folio
  mm/swap: stop using page->private on tail pages for THP_SWAP
  selftests/mm: fix WARNING comparing pointer to 0
  selftests: cgroup: fix test_kmem_memcg_deletion kernel mem check
  ...

The code is duplicated to perform the copy twice -- to handle buffer
wrap-around. Instead of the duplication, roll this into the loop.

(And add some blank lines around to have the code a bit more readable.)

Signed-off-by: "Jiri Slaby (SUSE)" <jirislaby@kernel.org>
Link: https://lore.kernel.org/r/20230827074147.2287-15-jirislaby@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

__process_echoes() contains ECHO_OPs processing. It is stuffed in a
while loop and the whole function is barely readable. Separate it to a
new function: n_tty_process_echo_ops().

Signed-off-by: "Jiri Slaby (SUSE)" <jirislaby@kernel.org>
Link: https://lore.kernel.org/r/20230827074147.2287-14-jirislaby@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>