[PATCH RFC 00/23] proc: convert the driver entries

[Christian Brauner]

This converts the proc entries of nubus, zorro, PCI, md, dasd and cio,
scsi, dell-smm, viafb, rndis, ipw2x00, sysrq and ALSA to what "proc:
let procfs own the data path" set up: procfs owns the seq_file, copies
in writes, copies out reads and copies ioctl arguments in and out, so
the entries' code only ever runs with the entry pinned and never
touches userspace memory.

One patch per subsystem and method, in the order seq_file, write, read,
ioctl. The PCI config space and ALSA's data entries take binary data at
positions and keep doing that: PROC_ENTRY_SHORT_WRITES for writes in
pieces, and ALSA's data entries ask for PROC_ENTRY_FULL_READS so that
reading all of one at once keeps working. They hand procfs' buffer to
the drivers, so struct snd_info_entry_ops changes along with them. The
PCI ioctls only pass values and the i8k ones encode the wrong sizes,
both list what is really copied. ALSA's ioctl hook that no driver
implements goes away. Where a write that is larger than anything the
entry parses now fails with -EINVAL from procfs I've called that out in
the commit.

The selftest writes to the file of a scsi_debug host from a buffer
backed by userfaultfd and removes the host while procfs copies in. On a
KASAN and lockdep kernel it fails without the series and passes with
it. Build tested per commit on x86_64 and with W=1 on the touched
objects on their own architectures. The entries I could get at in a VM
behave the same with and without the series.

This is on top of "proc: let procfs own the data path". The other three
conversion series don't depend on it and it doesn't depend on them.

Signed-off-by: Christian Brauner (Amutable) <brauner@xxxxxxxxxx>
---
Christian Brauner (23):
      nubus: let procfs own the seq_file of the resource files
      zorro: let procfs copy out reads
      PCI/proc: let procfs copy in config space writes
      PCI/proc: let procfs copy out config space reads
      PCI/proc: let procfs handle the ioctls
      md: let procfs own the seq_file of /proc/mdstat
      s390/dasd: let procfs copy in writes to /proc/dasd/statistics
      s390/cio: let procfs copy in writes
      scsi: let procfs own the seq_file of the host files
      scsi: core: let procfs copy in writes
      selftests/proc: check that a faulting writer doesn't hold up removal
      scsi: sg: let procfs own the seq_file of allow_dio and def_reserved_size
      scsi: sg: let procfs copy in writes
      scsi: esas2r: let procfs copy the ioctl argument of the ATTONode file
      hwmon: (dell-smm) let procfs copy the i8k ioctl arguments
      fbdev: viafb: let procfs copy in writes
      usb: gadget: function: rndis: let procfs copy in writes
      wifi: ipw2x00: let procfs copy in writes to the debug level
      tty: sysrq: let procfs copy in writes to /proc/sysrq-trigger
      ALSA: info: let procfs own the seq_file of text entries
      ALSA: info: let procfs copy in writes
      ALSA: info: let procfs copy out reads of data entries
      ALSA: info: drop the ioctl hook of data entries

 .../sound/kernel-api/writing-an-alsa-driver.rst    |  10 +-
 drivers/hwmon/dell-smm-hwmon.c                     |  48 ++---
 drivers/md/md.c                                    |  15 +-
 drivers/net/wireless/intel/ipw2x00/libipw_module.c |   7 +-
 drivers/nubus/proc.c                               |  12 +-
 drivers/pci/proc.c                                 |  69 ++++---
 drivers/s390/block/dasd_proc.c                     |  17 +-
 drivers/s390/cio/blacklist.c                       |  33 +---
 drivers/s390/cio/css.c                             |   4 +-
 drivers/scsi/esas2r/esas2r.h                       |   2 +
 drivers/scsi/esas2r/esas2r_ioctl.c                 |  58 +++---
 drivers/scsi/esas2r/esas2r_main.c                  |  44 ++++-
 drivers/scsi/scsi_devinfo.c                        |  29 +--
 drivers/scsi/scsi_proc.c                           |  55 ++----
 drivers/scsi/sg.c                                  |  44 ++---
 drivers/tty/sysrq.c                                |   9 +-
 drivers/usb/gadget/function/rndis.c                |   9 +-
 drivers/video/fbdev/via/viafbdev.c                 |  46 +++--
 drivers/zorro/proc.c                               |   7 +-
 include/sound/gus.h                                |   2 +-
 include/sound/info.h                               |   6 +-
 sound/core/info.c                                  |  57 +++---
 sound/drivers/opl4/opl4_proc.c                     |  23 +--
 sound/isa/gus/gus_dram.c                           |   7 +-
 sound/isa/gus/gus_mem_proc.c                       |   2 +-
 sound/pci/cs4281.c                                 |  10 +-
 sound/pci/cs46xx/cs46xx_lib.c                      |   5 +-
 sound/pci/emu10k1/emuproc.c                        |   8 +-
 sound/pci/mixart/mixart.c                          |  10 +-
 sound/usb/mixer_scarlett2.c                        |   9 +-
 tools/testing/selftests/proc/.gitignore            |   1 +
 tools/testing/selftests/proc/Makefile              |   1 +
 tools/testing/selftests/proc/config                |   3 +
 .../selftests/proc/proc-remove-slow-writer.c       | 203 +++++++++++++++++++++
 34 files changed, 480 insertions(+), 385 deletions(-)
---
base-commit: 65ba8f34ec886ec72b2c07ddc8cf3d815c32869d
change-id: 20261101-work-procfs-drivers-58cd83649658
prerequisite-change-id: 20261101-work-procfs-core-8fa4a4f412cf:v1
prerequisite-patch-id: 0474af12959624910718795bf86684383664c685
prerequisite-patch-id: 540aa9ea28adcbc54d8264f66314e29e3b8c9d49
prerequisite-patch-id: 2f7139d1c972c4439dccca610caa5f1288987a3d
prerequisite-patch-id: b0031a7c4855b7ec38259c59f30f65101a8fc4b5
prerequisite-patch-id: 0b7f226abf2b9ff41873a1aa55cf97747647d56b
prerequisite-patch-id: f63e345f897619af54813958046617c655fb7daf
prerequisite-patch-id: c0e21e762a2960e3324c5ab04634a7035e515fa6
prerequisite-patch-id: fd59c71eadd8f39c58b3baea93567bc093bc9b0e
prerequisite-patch-id: 5d52cc8a5c73e4c5ba16b8e24f51408c17583bf9
prerequisite-patch-id: 1f9179284e2f3314d4b46ac5e989089a21c7576c
prerequisite-patch-id: 10397bbf696bee16dc71eb79fff6c5e73842bcbc
prerequisite-patch-id: 9b44279dcf08912238d2f6438a3328a778a79a0c
prerequisite-patch-id: 16854b621a3a71dfc365aaf7abaa7f65adfe9f7e
prerequisite-patch-id: ca42eea21fae1fd1cd3518ab057c74b61ffd68fe
prerequisite-patch-id: 23255dc2be76b0479c083dbd4c897bfbb533aed5
prerequisite-patch-id: 82129c687ebf0a41b369893b92f2c038420ab801
prerequisite-patch-id: 56ad57a99a5bda075a9f4e844368974296744934
prerequisite-patch-id: 288b3cbaa11e01a778cc3d7beb6c0549aacf59f2
prerequisite-patch-id: a163b1549608652bfa5bd9ff93efa55b541010c4
prerequisite-patch-id: 78f067c343177e52d49ddfe9ee2992e602549869
prerequisite-patch-id: 19c12bc6e3fbed35acc1f657196b1a997f48cdfe
prerequisite-patch-id: 5800c3076694bad719954b2ad4d7448c6e013bfd
prerequisite-patch-id: 2a2f63d8843b159594b9eee6ddea028ce76a6270
prerequisite-patch-id: 40a1951d57906c4a1b98a4bd96a814b80339b9c5
prerequisite-patch-id: e2141077e69f20a2b27fab69c8d61d0686682f53
prerequisite-patch-id: c4d6018c26c40dc549d88330d23ce48f872c2b7f
prerequisite-patch-id: 6de8ec17746031bc6d1d9ac262c5be0f905fcd79
prerequisite-patch-id: b87bcb167884605bff1fd0f2ed8a88942d07efd5
prerequisite-patch-id: cfa9a8b4c67e20cfd22d77035bfd21ee96ab3298
prerequisite-patch-id: abf3482ed2399b7b2e1ee72e937af05bb9200667
prerequisite-patch-id: 02c175b2dee565a85b3308ecf2ec8e3c9a029e0f
prerequisite-patch-id: 4ed6b3d3d45de49d4967e88ba4e7f03372775f55
prerequisite-patch-id: dbe02fe3f784776fda5e7ae99f077bef0cd4b48d
prerequisite-patch-id: 53edc9a95afff57c4acba40095a8054924261ea2
prerequisite-patch-id: cf9ce0099005fd3bc31a1e15131d48e315ac3bee
prerequisite-patch-id: 16a657a5d0046068dbace29e7ea046ac1441f46f
prerequisite-patch-id: efeb2d6f7df71d5dede2c1d12fe999a28e38aab9
prerequisite-patch-id: e6ffe2a5c3ee5645f56c8366b568fbc9f140848c
prerequisite-patch-id: 117db27dcdef433de7c6be5e95973cac1e373927
prerequisite-patch-id: a0844aa26ffb65ccb362b88ef6c2f4758e15edbf
prerequisite-patch-id: 143fb91bddf33068b6ee11e205818c4c2815e23d
prerequisite-patch-id: 6490e4da1cb2f543683bd164bc9a5a1c943057e7
prerequisite-patch-id: cdefca57d3c552fb6f6b928699edd85f33be25fd
prerequisite-patch-id: 2f0fdb970ddd760d85ff5d2caad0b96348270182
prerequisite-patch-id: f2aa468ff5cbb1cabab3f70e1b8eeee0286cfb4a
prerequisite-patch-id: 037030d95eeb7c49b1e43f638ec954f2cebbcfb1
prerequisite-patch-id: 487141c49e2548310bfb6c2a0964a78f08b285a9
prerequisite-patch-id: c3d3008819fa5629a18142ec9ba6d7024ade7fdb
prerequisite-patch-id: ba15e7c86b60ccc2f0f7ee4c9bc99073068757bc
prerequisite-patch-id: 9423f410b99853693db06c29f12f1c08278b050d
prerequisite-patch-id: 4e7966978e4b11c4d843831f312cdcd5b848f00c
prerequisite-patch-id: 3d24be1897a624d519ef144801f76d152c7528a9
prerequisite-patch-id: 3b4d9fe7b26f6b7b9b3f7725ea333df357107c44
prerequisite-patch-id: 7d9dd345428baeb88c862ef902612f7160dc1d8c