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Finn Thain ca09dfc3cf serial/pmac_zilog: Remove flawed mitigation for rx irq flood
commit 1be3226445 upstream.

The mitigation was intended to stop the irq completely. That may be
better than a hard lock-up but it turns out that you get a crash anyway
if you're using pmac_zilog as a serial console:

ttyPZ0: pmz: rx irq flood !
BUG: spinlock recursion on CPU#0, swapper/0

That's because the pr_err() call in pmz_receive_chars() results in
pmz_console_write() attempting to lock a spinlock already locked in
pmz_interrupt(). With CONFIG_DEBUG_SPINLOCK=y, this produces a fatal
BUG splat. The spinlock in question is the one in struct uart_port.

Even when it's not fatal, the serial port rx function ceases to work.
Also, the iteration limit doesn't play nicely with QEMU, as can be
seen in the bug report linked below.

A web search for other reports of the error message "pmz: rx irq flood"
didn't produce anything. So I don't think this code is needed any more.
Remove it.

Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Aneesh Kumar K.V <aneesh.kumar@kernel.org>
Cc: Naveen N. Rao <naveen.n.rao@linux.ibm.com>
Cc: Andy Shevchenko <andy.shevchenko@gmail.com>
Cc: stable@kernel.org
Cc: linux-m68k@lists.linux-m68k.org
Link: https://github.com/vivier/qemu-m68k/issues/44
Link: https://lore.kernel.org/all/1078874617.9746.36.camel@gaston/
Acked-by: Michael Ellerman <mpe@ellerman.id.au>
Fixes: 1da177e4c3 ("Linux-2.6.12-rc2")
Cc: stable <stable@kernel.org>
Signed-off-by: Finn Thain <fthain@linux-m68k.org>
Link: https://lore.kernel.org/r/e853cf2c762f23101cd2ddec0cc0c2be0e72685f.1712568223.git.fthain@linux-m68k.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-04-27 17:12:58 +02:00
Documentation x86/bugs: Remove CONFIG_BHI_MITIGATION_AUTO and spectre_bhi=auto 2024-04-17 11:23:41 +02:00
LICENSES LICENSES: Add the copyleft-next-0.3.1 license 2022-11-08 15:44:01 +01:00
arch x86/cpufeatures: Fix dependencies for GFNI, VAES, and VPCLMULQDQ 2024-04-27 17:12:57 +02:00
block block: propagate partition scanning errors to the BLKRRPART ioctl 2024-04-27 17:12:57 +02:00
certs This update includes the following changes: 2023-11-02 16:15:30 -10:00
crypto Revert "crypto: pkcs7 - remove sha1 support" 2024-04-03 15:32:31 +02:00
drivers serial/pmac_zilog: Remove flawed mitigation for rx irq flood 2024-04-27 17:12:58 +02:00
fs NFSD: fix endianness issue in nfsd4_encode_fattr4 2024-04-27 17:12:53 +02:00
include block: propagate partition scanning errors to the BLKRRPART ioctl 2024-04-27 17:12:57 +02:00
init fs/proc: Skip bootloader comment if no embedded kernel parameters 2024-04-17 11:23:36 +02:00
io_uring io_uring: Fix io_cqring_wait() not restoring sigmask on get_timespec64() failure 2024-04-27 17:12:47 +02:00
ipc shm: Slim down dependencies 2023-12-20 19:26:31 -05:00
kernel x86/cpu: Actually turn off mitigations by default for SPECULATION_MITIGATIONS=n 2024-04-17 11:23:39 +02:00
lib lib: checksum: hide unused expected_csum_ipv6_magic[] 2024-04-17 11:23:28 +02:00
mm userfaultfd: change src_folio after ensuring it's unpinned in UFFDIO_MOVE 2024-04-27 17:12:54 +02:00
net net/sched: Fix mirred deadlock on device recursion 2024-04-27 17:12:53 +02:00
rust Rust changes for v6.8 2024-01-11 13:05:41 -08:00
samples work around gcc bugs with 'asm goto' with outputs 2024-02-09 15:57:48 -08:00
scripts gcc-plugins/stackleak: Avoid .head.text section 2024-04-13 13:10:11 +02:00
security selinux: avoid dereference of garbage after mount failure 2024-04-10 16:38:01 +02:00
sound ALSA: hda/realtek - Enable audio jacks of Haier Boyue G42 with ALC269VC 2024-04-27 17:12:57 +02:00
tools selftests/powerpc/papr-vpd: Fix missing variable initialization 2024-04-27 17:12:56 +02:00
usr Kbuild updates for v6.8 2024-01-18 17:57:07 -08:00
virt KVM: Always flush async #PF workqueue when vCPU is being destroyed 2024-04-03 15:32:03 +02:00
.clang-format clang-format: Update with v6.7-rc4's `for_each` macro list 2023-12-08 23:54:38 +01:00
.cocciconfig
.editorconfig Add .editorconfig file for basic formatting 2023-12-28 16:22:47 +09:00
.get_maintainer.ignore get_maintainer: add Alan to .get_maintainer.ignore 2022-08-20 15:17:44 -07:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore Add .editorconfig file for basic formatting 2023-12-28 16:22:47 +09:00
.mailmap drm fixes for 6.8 final 2024-03-08 12:44:56 -08:00
.rustfmt.toml rust: add `.rustfmt.toml` 2022-09-28 09:02:20 +02:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: supplement of zswap maintainers update 2024-01-25 23:52:21 -08:00
Kbuild Kbuild updates for v6.1 2022-10-10 12:00:45 -07:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS drm fixes for 6.8 final 2024-03-08 12:44:56 -08:00
Makefile Linux 6.8.7 2024-04-17 11:23:43 +02:00
README

README

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.