48 Commits
Author SHA1 Message Date
Krzysztof KozlowskiandBjorn Helgaas c4cac4a15c PCI: pnv_php: Simplify with scoped for each OF child loop
Use scoped for-each loop when iterating over device nodes to make code a
bit simpler.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@oss.qualcomm.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com>
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://patch.msgid.link/20260317133322.266102-7-krzysztof.kozlowski@oss.qualcomm.com
2026-03-17 16:19:03 -05:00
Linus Torvalds bf4afc53b7 Convert 'alloc_obj' family to use the new default GFP_KERNEL argument
This was done entirely with mindless brute force, using

    git grep -l '\<k[vmz]*alloc_objs*(.*, GFP_KERNEL)' |
        xargs sed -i 's/\(alloc_objs*(.*\), GFP_KERNEL)/\1)/'

to convert the new alloc_obj() users that had a simple GFP_KERNEL
argument to just drop that argument.

Note that due to the extreme simplicity of the scripting, any slightly
more complex cases spread over multiple lines would not be triggered:
they definitely exist, but this covers the vast bulk of the cases, and
the resulting diff is also then easier to check automatically.

For the same reason the 'flex' versions will be done as a separate
conversion.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2026-02-21 17:09:51 -08:00
Kees Cook 69050f8d6d treewide: Replace kmalloc with kmalloc_obj for non-scalar types
This is the result of running the Coccinelle script from
scripts/coccinelle/api/kmalloc_objs.cocci. The script is designed to
avoid scalar types (which need careful case-by-case checking), and
instead replace kmalloc-family calls that allocate struct or union
object instances:

Single allocations:	kmalloc(sizeof(TYPE), ...)
are replaced with:	kmalloc_obj(TYPE, ...)

Array allocations:	kmalloc_array(COUNT, sizeof(TYPE), ...)
are replaced with:	kmalloc_objs(TYPE, COUNT, ...)

Flex array allocations:	kmalloc(struct_size(PTR, FAM, COUNT), ...)
are replaced with:	kmalloc_flex(*PTR, FAM, COUNT, ...)

(where TYPE may also be *VAR)

The resulting allocations no longer return "void *", instead returning
"TYPE *".

Signed-off-by: Kees Cook <kees@kernel.org>
2026-02-21 01:02:28 -08:00
Marco CrivellariandBjorn Helgaas 78f5d0d5a2 PCI: Add WQ_PERCPU to alloc_workqueue() users
Currently work items enqueued by schedule_delayed_work() use "system_wq" (a
per-CPU wq), while queue_delayed_work() uses WORK_CPU_UNBOUND (used when a
CPU is not specified). The same applies to schedule_work() that is using
system_wq and queue_work(), that makes use again of WORK_CPU_UNBOUND.  This
lack of consistency cannot be addressed without refactoring the API.

alloc_workqueue() treats all queues as per-CPU by default, while unbound
workqueues must opt-in via WQ_UNBOUND.

This default is suboptimal: most workloads benefit from unbound queues,
allowing the scheduler to place worker threads where they're needed and
reducing noise when CPUs are isolated.

This continues the effort to refactor workqueue APIs, which began with the
introduction of new workqueues and a new alloc_workqueue() flag in:

  128ea9f6cc ("workqueue: Add system_percpu_wq and system_dfl_wq")
  930c2ea566 ("workqueue: Add new WQ_PERCPU flag")

Add WQ_PERCPU to explicitly request alloc_workqueue() to be per-CPU when
WQ_UNBOUND has not been specified.

With the introduction of the WQ_PERCPU flag (equivalent to !WQ_UNBOUND),
any alloc_workqueue() caller that doesn't explicitly specify WQ_UNBOUND
must now use WQ_PERCPU.

Once migration is complete, WQ_UNBOUND can be removed and unbound will
become the implicit default.

Suggested-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Marco Crivellari <marco.crivellari@suse.com>
[bhelgaas: squash similar commits]
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Link: https://patch.msgid.link/20251107142526.234685-1-marco.crivellari@suse.com
Link: https://patch.msgid.link/20251107142835.237636-1-marco.crivellari@suse.com
Link: https://patch.msgid.link/20251107143108.240025-1-marco.crivellari@suse.com
Link: https://patch.msgid.link/20251107143335.242342-1-marco.crivellari@suse.com
Link: https://patch.msgid.link/20251107143624.244978-1-marco.crivellari@suse.com
2025-12-29 10:18:02 -06:00
Timothy PearsonandMadhavan Srinivasan a8f2b96ca9 PCI: pnv_php: Enable third attention indicator state
The PCIe specification allows three attention indicator states, on, off,
and blink.  Enable all three states instead of basic on / off control.

This changes the userspace API (writes to the sysfs "attention" file) to
match the behavior of pciehp.  Here's the comparison of previous and new
indicator behavior:

  Value  Previous   New Behavior
  -----  --------   ------------------------
    0    off        (reserved, so undefined)
    1    on         on
    2    on         blink
    3    on         off

Signed-off-by: Timothy Pearson <tpearson@raptorengineering.com>
[bhelgaas: add specifics of behavior change]
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/1210309411.1359866.1752615582001.JavaMail.zimbra@raptorengineeringinc.com
2025-07-26 13:09:20 +05:30
Timothy PearsonandMadhavan Srinivasan a2a2a6fc24 PCI: pnv_php: Fix surprise plug detection and recovery
The existing PowerNV hotplug code did not handle surprise plug events
correctly, leading to a complete failure of the hotplug system after device
removal and a required reboot to detect new devices.

This comes down to two issues:

 1) When a device is surprise removed, often the bridge upstream
    port will cause a PE freeze on the PHB.  If this freeze is not
    cleared, the MSI interrupts from the bridge hotplug notification
    logic will not be received by the kernel, stalling all plug events
    on all slots associated with the PE.

 2) When a device is removed from a slot, regardless of surprise or
    programmatic removal, the associated PHB/PE ls left frozen.
    If this freeze is not cleared via a fundamental reset, skiboot
    is unable to clear the freeze and cannot retrain / rescan the
    slot.  This also requires a reboot to clear the freeze and redetect
    the device in the slot.

Issue the appropriate unfreeze and rescan commands on hotplug events,
and don't oops on hotplug if pci_bus_to_OF_node() returns NULL.

Signed-off-by: Timothy Pearson <tpearson@raptorengineering.com>
[bhelgaas: tidy comments]
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/171044224.1359864.1752615546988.JavaMail.zimbra@raptorengineeringinc.com
2025-07-26 13:09:15 +05:30
Timothy PearsonandMadhavan Srinivasan 80f9fc2362 PCI: pnv_php: Work around switches with broken presence detection
The Microsemi Switchtec PM8533 PFX 48xG3 [11f8:8533] PCIe switch system
was observed to incorrectly assert the Presence Detect Set bit in its
capabilities when tested on a Raptor Computing Systems Blackbird system,
resulting in the hot insert path never attempting a rescan of the bus
and any downstream devices not being re-detected.

Work around this by additionally checking whether the PCIe data link is
active or not when performing presence detection on downstream switches'
ports, similar to the pciehp_hpc.c driver.

Signed-off-by: Shawn Anastasio <sanastasio@raptorengineering.com>
Signed-off-by: Timothy Pearson <tpearson@raptorengineering.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/505981576.1359853.1752615415117.JavaMail.zimbra@raptorengineeringinc.com
2025-07-26 13:07:42 +05:30
Timothy PearsonandMadhavan Srinivasan 4668619092 PCI: pnv_php: Clean up allocated IRQs on unplug
When the root of a nested PCIe bridge configuration is unplugged, the
pnv_php driver leaked the allocated IRQ resources for the child bridges'
hotplug event notifications, resulting in a panic.

Fix this by walking all child buses and deallocating all its IRQ resources
before calling pci_hp_remove_devices().

Also modify the lifetime of the workqueue at struct pnv_php_slot::wq so
that it is only destroyed in pnv_php_free_slot(), instead of
pnv_php_disable_irq(). This is required since pnv_php_disable_irq() will
now be called by workers triggered by hot unplug interrupts, so the
workqueue needs to stay allocated.

The abridged kernel panic that occurs without this patch is as follows:

  WARNING: CPU: 0 PID: 687 at kernel/irq/msi.c:292 msi_device_data_release+0x6c/0x9c
  CPU: 0 UID: 0 PID: 687 Comm: bash Not tainted 6.14.0-rc5+ #2
  Call Trace:
   msi_device_data_release+0x34/0x9c (unreliable)
   release_nodes+0x64/0x13c
   devres_release_all+0xc0/0x140
   device_del+0x2d4/0x46c
   pci_destroy_dev+0x5c/0x194
   pci_hp_remove_devices+0x90/0x128
   pci_hp_remove_devices+0x44/0x128
   pnv_php_disable_slot+0x54/0xd4
   power_write_file+0xf8/0x18c
   pci_slot_attr_store+0x40/0x5c
   sysfs_kf_write+0x64/0x78
   kernfs_fop_write_iter+0x1b0/0x290
   vfs_write+0x3bc/0x50c
   ksys_write+0x84/0x140
   system_call_exception+0x124/0x230
   system_call_vectored_common+0x15c/0x2ec

Signed-off-by: Shawn Anastasio <sanastasio@raptorengineering.com>
Signed-off-by: Timothy Pearson <tpearson@raptorengineering.com>
[bhelgaas: tidy comments]
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/2013845045.1359852.1752615367790.JavaMail.zimbra@raptorengineeringinc.com
2025-07-26 13:07:10 +05:30
Krishna KumarandMichael Ellerman 335e35b748 pci/hotplug/pnv_php: Fix hotplug driver crash on Powernv
The hotplug driver for powerpc (pci/hotplug/pnv_php.c) causes a kernel
crash when we try to hot-unplug/disable the PCIe switch/bridge from
the PHB.

The crash occurs because although the MSI data structure has been
released during disable/hot-unplug path and it has been assigned
with NULL, still during unregistration the code was again trying to
explicitly disable the MSI which causes the NULL pointer dereference and
kernel crash.

The patch fixes the check during unregistration path to prevent invoking
pci_disable_msi/msix() since its data structure is already freed.

Reported-by: Timothy Pearson <tpearson@raptorengineering.com>
Closes: https://lore.kernel.org/all/1981605666.2142272.1703742465927.JavaMail.zimbra@raptorengineeringinc.com/
Acked-by: Bjorn Helgaas <bhelgaas@google.com>
Tested-by: Shawn Anastasio <sanastasio@raptorengineering.com>
Signed-off-by: Krishna Kumar <krishnak@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20240701074513.94873-2-krishnak@linux.ibm.com
2024-07-04 23:10:40 +10:00
Ilpo JärvinenandBjorn Helgaas abaaac4845 PCI: hotplug: Use FIELD_GET/PREP()
Instead of handcrafted shifts to handle register fields, use
FIELD_GET/FIELD_PREP().

Link: https://lore.kernel.org/r/20231018113254.17616-4-ilpo.jarvinen@linux.intel.com
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
2023-10-24 10:54:04 -05:00
Christophe LeroyandBjorn Helgaas b2851926c6 PCI: hotplug: Clean up include files
arch/powerpc/include/asm/prom.h includes some headers that it doesn't need
itself.  Add the missing headers to files that include prom.h so we can
remove them from prom.h.

Link: https://lore.kernel.org/r/79201f5fae8d003164ac36ed3be7789db1bc5ab4.1648833421.git.christophe.leroy@csgroup.eu
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
2022-04-05 11:13:33 -05:00
Amey NarkhedeandBjorn Helgaas 9bdc81ce44 PCI: Change the type of probe argument in reset functions
Change the type of probe argument in functions which implement reset
methods from int to bool to make the context and intent clear.

Suggested-by: Alex Williamson <alex.williamson@redhat.com>
Link: https://lore.kernel.org/r/20210817180500.1253-10-ameynarkhede03@gmail.com
Signed-off-by: Amey Narkhede <ameynarkhede03@gmail.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
2021-08-18 17:32:42 -05:00
Frederic BarratandMichael Ellerman 748ac391ab pci/hotplug/pnv-php: Wrap warnings in macro
An opencapi slot doesn't have an associated bridge device. It's not
needed for operation, but any warning is displayed through pci_warn()
which uses the pci_dev struct of the assocated bridge device. So wrap
those warning so that a different trace mechanism can be used if it's
an opencapi slot.

Reviewed-by: Alastair D'Silva <alastair@d-silva.org>
Reviewed-by: Andrew Donnellan <ajd@linux.ibm.com>
Signed-off-by: Frederic Barrat <fbarrat@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20191121134918.7155-11-fbarrat@linux.ibm.com
2020-01-23 21:31:17 +11:00
Frederic BarratandMichael Ellerman be1611e043 pci/hotplug/pnv-php: Relax check when disabling slot
The driver only allows to disable a slot in the POPULATED
state. However, if an error occurs while enabling the slot, say
because the link couldn't be trained, then the POPULATED state may not
be reached, yet the power state of the slot is on. So allow to disable
a slot in the REGISTERED state. Removing the devices will do nothing
since it's not populated, and we'll set the power state of the slot
back to off.

Reviewed-by: Alastair D'Silva <alastair@d-silva.org>
Reviewed-by: Andrew Donnellan <ajd@linux.ibm.com>
Signed-off-by: Frederic Barrat <fbarrat@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20191121134918.7155-10-fbarrat@linux.ibm.com
2020-01-23 21:31:17 +11:00
Frederic BarratandMichael Ellerman ea53919b15 pci/hotplug/pnv-php: Register opencapi slots
Add the opencapi PHBs to the list of PHBs being scanned to look for
slots.

Signed-off-by: Frederic Barrat <fbarrat@linux.ibm.com>
Reviewed-by: Andrew Donnellan <ajd@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20191121134918.7155-9-fbarrat@linux.ibm.com
2020-01-23 21:31:17 +11:00
Frederic BarratandMichael Ellerman 323c2a26ff pci/hotplug/pnv-php: Improve error msg on power state change failure
When changing the slot state, if opal hits an error and tells as such
in the asynchronous reply, the warning "Wrong msg" is logged, which is
rather confusing. Instead we can reuse the better message which is
already used when we couldn't submit the asynchronous opal request
initially.

Reviewed-by: Alastair D'Silva <alastair@d-silva.org>
Reviewed-by: Andrew Donnellan <ajd@linux.ibm.com>
Signed-off-by: Frederic Barrat <fbarrat@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20191121134918.7155-8-fbarrat@linux.ibm.com
2020-01-23 21:31:17 +11:00
Frederic BarratandMichael Ellerman 658ab186dd pci/hotplug/pnv-php: Remove erroneous warning
On powernv, when removing a device through hotplug, the following
warning is logged:

     Invalid refcount <.> on <...>

It may be incorrect, the refcount may be set to a higher value than 1
and be valid. of_detach_node() can drop more than one reference. As it
doesn't seem trivial to assert the correct value, let's remove the
warning.

Reviewed-by: Alastair D'Silva <alastair@d-silva.org>
Reviewed-by: Andrew Donnellan <ajd@linux.ibm.com>
Signed-off-by: Frederic Barrat <fbarrat@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20191121134918.7155-7-fbarrat@linux.ibm.com
2020-01-23 21:31:17 +11:00
Oliver O'HalloranandMichael Ellerman 018c49e999 pci-hotplug/pnv_php: Add attention indicator support
pnv_php is generally used with PCIe bridges which provide a native
interface for setting the attention and power indicator LEDs. Wire up
those interfaces even if firmware does not have support for them (yet...)

Signed-off-by: Oliver O'Halloran <oohall@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20190903101605.2890-11-oohall@gmail.com
2019-09-05 14:22:39 +10:00
Oliver O'HalloranandMichael Ellerman a839bd87a2 pci-hotplug/pnv_php: Add support for IODA3 Power9 PHBs
Currently we check that an IODA2 compatible PHB is upstream of this slot.
This is mainly to avoid pnv_php creating slots for the various "virtual
PHBs" that we create for NVLink. There's no real need for this restriction
so allow it on IODA3.

Signed-off-by: Oliver O'Halloran <oohall@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20190903101605.2890-10-oohall@gmail.com
2019-09-05 14:22:39 +10:00
Oliver O'HalloranandMichael Ellerman 7fd1fe4e48 pci-hotplug/pnv_php: Add a reset_slot() callback
When performing EEH recovery of devices in a hotplug slot we need to use
the slot driver's ->reset_slot() callback to prevent spurious hotplug
events due to spurious DLActive and PresDet change interrupts. Add a
reset_slot() callback to pnv_php so we can handle recovery of devices
in pnv_php managed slots.

Signed-off-by: Oliver O'Halloran <oohall@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20190903101605.2890-9-oohall@gmail.com
2019-09-05 14:22:39 +10:00
Linus Torvalds 685f7e4f16 Merge tag 'powerpc-4.20-1' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux
Pull powerpc updates from Michael Ellerman:
 "Notable changes:

   - A large series to rewrite our SLB miss handling, replacing a lot of
     fairly complicated asm with much fewer lines of C.

   - Following on from that, we now maintain a cache of SLB entries for
     each process and preload them on context switch. Leading to a 27%
     speedup for our context switch benchmark on Power9.

   - Improvements to our handling of SLB multi-hit errors. We now print
     more debug information when they occur, and try to continue running
     by flushing the SLB and reloading, rather than treating them as
     fatal.

   - Enable THP migration on 64-bit Book3S machines (eg. Power7/8/9).

   - Add support for physical memory up to 2PB in the linear mapping on
     64-bit Book3S. We only support up to 512TB as regular system
     memory, otherwise the percpu allocator runs out of vmalloc space.

   - Add stack protector support for 32 and 64-bit, with a per-task
     canary.

   - Add support for PTRACE_SYSEMU and PTRACE_SYSEMU_SINGLESTEP.

   - Support recognising "big cores" on Power9, where two SMT4 cores are
     presented to us as a single SMT8 core.

   - A large series to cleanup some of our ioremap handling and PTE
     flags.

   - Add a driver for the PAPR SCM (storage class memory) interface,
     allowing guests to operate on SCM devices (acked by Dan).

   - Changes to our ftrace code to handle very large kernels, where we
     need to use a trampoline to get to ftrace_caller().

  And many other smaller enhancements and cleanups.

  Thanks to: Alan Modra, Alistair Popple, Aneesh Kumar K.V, Anton
  Blanchard, Aravinda Prasad, Bartlomiej Zolnierkiewicz, Benjamin
  Herrenschmidt, Breno Leitao, Cédric Le Goater, Christophe Leroy,
  Christophe Lombard, Dan Carpenter, Daniel Axtens, Finn Thain, Gautham
  R. Shenoy, Gustavo Romero, Haren Myneni, Hari Bathini, Jia Hongtao,
  Joel Stanley, John Allen, Laurent Dufour, Madhavan Srinivasan, Mahesh
  Salgaonkar, Mark Hairgrove, Masahiro Yamada, Michael Bringmann,
  Michael Neuling, Michal Suchanek, Murilo Opsfelder Araujo, Nathan
  Fontenot, Naveen N. Rao, Nicholas Piggin, Nick Desaulniers, Oliver
  O'Halloran, Paul Mackerras, Petr Vorel, Rashmica Gupta, Reza Arbab,
  Rob Herring, Sam Bobroff, Samuel Mendoza-Jonas, Scott Wood, Stan
  Johnson, Stephen Rothwell, Stewart Smith, Suraj Jitindar Singh, Tyrel
  Datwyler, Vaibhav Jain, Vasant Hegde, YueHaibing, zhong jiang"

* tag 'powerpc-4.20-1' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux: (221 commits)
  Revert "selftests/powerpc: Fix out-of-tree build errors"
  powerpc/msi: Fix compile error on mpc83xx
  powerpc: Fix stack protector crashes on CPU hotplug
  powerpc/traps: restore recoverability of machine_check interrupts
  powerpc/64/module: REL32 relocation range check
  powerpc/64s/radix: Fix radix__flush_tlb_collapsed_pmd double flushing pmd
  selftests/powerpc: Add a test of wild bctr
  powerpc/mm: Fix page table dump to work on Radix
  powerpc/mm/radix: Display if mappings are exec or not
  powerpc/mm/radix: Simplify split mapping logic
  powerpc/mm/radix: Remove the retry in the split mapping logic
  powerpc/mm/radix: Fix small page at boundary when splitting
  powerpc/mm/radix: Fix overuse of small pages in splitting logic
  powerpc/mm/radix: Fix off-by-one in split mapping logic
  powerpc/ftrace: Handle large kernel configs
  powerpc/mm: Fix WARN_ON with THP NUMA migration
  selftests/powerpc: Fix out-of-tree build errors
  powerpc/time: no steal_time when CONFIG_PPC_SPLPAR is not selected
  powerpc/time: Only set CONFIG_ARCH_HAS_SCALED_CPUTIME on PPC64
  powerpc/time: isolate scaled cputime accounting in dedicated functions.
  ...
2018-10-26 14:36:21 -07:00
Sam BobroffandMichael Ellerman e762bb891a powerpc/eeh: Cleanup eeh_pe_state_mark()
Currently, eeh_pe_state_mark() marks a PE (and it's children) with a
state and then performs additional processing if that state included
EEH_PE_ISOLATED.

The state parameter is always a constant at the call site, so
rearrange eeh_pe_state_mark() into two functions and just call the
appropriate one at each site.

Signed-off-by: Sam Bobroff <sbobroff@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
2018-10-13 22:21:25 +11:00
YueHaibingandBjorn Helgaas 74171e9dab PCI: pnv_php: Use kmemdup()
Use kmemdup() rather than duplicating its implementation.

Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: Michael Ellerman <mpe@ellerman.id.au>
2018-10-02 16:04:40 -05:00
Lukas WunnerandBjorn Helgaas 125450f814 PCI: hotplug: Embed hotplug_slot
When the PCI hotplug core and its first user, cpqphp, were introduced in
February 2002 with historic commit a8a2069f432c, cpqphp allocated a slot
struct for its internal use plus a hotplug_slot struct to be registered
with the hotplug core and linked the two with pointers:
https://git.kernel.org/tglx/history/c/a8a2069f432c

Nowadays, the predominant pattern in the tree is to embed ("subclass")
such structures in one another and cast to the containing struct with
container_of().  But it wasn't until July 2002 that container_of() was
introduced with historic commit ec4f214232cf:
https://git.kernel.org/tglx/history/c/ec4f214232cf

pnv_php, introduced in 2016, did the right thing and embedded struct
hotplug_slot in its internal struct pnv_php_slot, but all other drivers
cargo-culted cpqphp's design and linked separate structs with pointers.

Embedding structs is preferrable to linking them with pointers because
it requires fewer allocations, thereby reducing overhead and simplifying
error paths.  Casting an embedded struct to the containing struct
becomes a cheap subtraction rather than a dereference.  And having fewer
pointers reduces the risk of them pointing nowhere either accidentally
or due to an attack.

Convert all drivers to embed struct hotplug_slot in their internal slot
struct.  The "private" pointer in struct hotplug_slot thereby becomes
unused, so drop it.

Signed-off-by: Lukas Wunner <lukas@wunner.de>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Tyrel Datwyler <tyreld@linux.vnet.ibm.com>  # drivers/pci/hotplug/rpa*
Acked-by: Sebastian Ott <sebott@linux.ibm.com>        # drivers/pci/hotplug/s390*
Acked-by: Andy Shevchenko <andy.shevchenko@gmail.com> # drivers/platform/x86
Cc: Len Brown <lenb@kernel.org>
Cc: Scott Murray <scott@spiteful.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Oliver OHalloran <oliveroh@au1.ibm.com>
Cc: Gavin Shan <gwshan@linux.vnet.ibm.com>
Cc: Gerald Schaefer <gerald.schaefer@de.ibm.com>
Cc: Corentin Chary <corentin.chary@gmail.com>
Cc: Darren Hart <dvhart@infradead.org>
2018-09-18 17:52:15 -05:00
Lukas WunnerandBjorn Helgaas a7da21613c PCI: hotplug: Drop hotplug_slot_info
Ever since the PCI hotplug core was introduced in 2002, drivers had to
allocate and register a struct hotplug_slot_info for every slot:
https://git.kernel.org/tglx/history/c/a8a2069f432c

Apparently the idea was that drivers furnish the hotplug core with an
up-to-date card presence status, power status, latch status and
attention indicator status as well as notify the hotplug core of changes
thereof.  However only 4 out of 12 hotplug drivers bother to notify the
hotplug core with pci_hp_change_slot_info() and the hotplug core never
made any use of the information:  There is just a single macro in
pci_hotplug_core.c, GET_STATUS(), which uses the hotplug_slot_info if
the driver lacks the corresponding callback in hotplug_slot_ops.  The
macro is called when the user reads the attribute via sysfs.

Now, if the callback isn't defined, the attribute isn't exposed in sysfs
in the first place (see e.g. has_power_file()).  There are only two
situations when the hotplug_slot_info would actually be accessed:

* If the driver defines ->enable_slot or ->disable_slot but not
  ->get_power_status.

* If the driver defines ->set_attention_status but not
  ->get_attention_status.

There is no driver doing the former and just a single driver doing the
latter, namely pnv_php.c.  Amend it with a ->get_attention_status
callback.  With that, the hotplug_slot_info becomes completely unused by
the PCI hotplug core.  But a few drivers use it internally as a cache:

cpcihp uses it to cache the latch_status and adapter_status.
cpqhp uses it to cache the adapter_status.
pnv_php and rpaphp use it to cache the attention_status.
shpchp uses it to cache all four values.

Amend these drivers to cache the information in their private slot
struct.  shpchp's slot struct already contains members to cache the
power_status and adapter_status, so additional members are only needed
for the other two values.  In the case of cpqphp, the cached value is
only accessed in a single place, so instead of caching it, read the
current value from the hardware.

Caution:  acpiphp, cpci, cpqhp, shpchp, asus-wmi and eeepc-laptop
populate the hotplug_slot_info with initial values on probe.  That code
is herewith removed.  There is a theoretical chance that the code has
side effects without which the driver fails to function, e.g. if the
ACPI method to read the adapter status needs to be executed at least
once on probe.  That seems unlikely to me, still maintainers should
review the changes carefully for this possibility.

Rafael adds: "I'm not aware of any case in which it will break anything,
[...] but if that happens, it may be necessary to add the execution of
the control methods in question directly to the initialization part."

Signed-off-by: Lukas Wunner <lukas@wunner.de>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Tyrel Datwyler <tyreld@linux.vnet.ibm.com>  # drivers/pci/hotplug/rpa*
Acked-by: Sebastian Ott <sebott@linux.ibm.com>        # drivers/pci/hotplug/s390*
Acked-by: Andy Shevchenko <andy.shevchenko@gmail.com> # drivers/platform/x86
Cc: Len Brown <lenb@kernel.org>
Cc: Scott Murray <scott@spiteful.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Oliver OHalloran <oliveroh@au1.ibm.com>
Cc: Gavin Shan <gwshan@linux.vnet.ibm.com>
Cc: Gerald Schaefer <gerald.schaefer@de.ibm.com>
Cc: Corentin Chary <corentin.chary@gmail.com>
Cc: Darren Hart <dvhart@infradead.org>
2018-09-18 17:52:15 -05:00