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Jens Axboe 5753dbb326 io_uring/fdinfo: remove need for sqpoll lock for thread/pid retrieval
[ Upstream commit a0d45c3f59 ]

A previous commit added a trylock for getting the SQPOLL thread info via
fdinfo, but this introduced a regression where we often fail to get it if
the thread is busy. For that case, we end up not printing the current CPU
and PID info.

Rather than rely on this lock, just print the pid we already stored in
the io_sq_data struct, and ensure we update the current CPU every time
we've slept or potentially rescheduled. The latter won't potentially be
100% accurate, but that wasn't the case before either as the task can
get migrated at any time unless it has been pinned at creation time.

We retain keeping the io_sq_data dereference inside the ctx->uring_lock,
as it has always been, as destruction of the thread and data happen below
that. We could make this RCU safe, but there's little point in doing that.

With this, we always print the last valid information we had, rather than
have spurious outputs with missing information.

Fixes: 7644b1a1c9 ("io_uring/fdinfo: lock SQ thread while retrieving thread cpu/pid")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2023-11-28 17:19:52 +00:00
arch riscv: split cache ops out of dma-noncoherent.c 2023-11-28 17:19:49 +00:00
block blk-mq: make sure active queue usage is held for bio_integrity_prep() 2023-11-28 17:19:51 +00:00
certs certs: Reference revocation list for all keyrings 2023-08-17 20:12:41 +00:00
crypto crypto: pcrypt - Fix hungtask for PADATA_RESET 2023-11-28 17:19:42 +00:00
Documentation dt-bindings: serial: fix regex pattern for matching serial node children 2023-11-28 17:19:48 +00:00
drivers gve: Fixes for napi_poll when budget is 0 2023-11-28 17:19:52 +00:00
fs gfs2: Silence "suspicious RCU usage in gfs2_permission" warning 2023-11-28 17:19:49 +00:00
include netfilter: nf_tables: fix pointer math issue in nft_byteorder_eval() 2023-11-28 17:19:52 +00:00
init x86/retpoline: Make sure there are no unconverted return thunks due to KCSAN 2023-11-28 17:19:36 +00:00
io_uring io_uring/fdinfo: remove need for sqpoll lock for thread/pid retrieval 2023-11-28 17:19:52 +00:00
ipc Add x86 shadow stack support 2023-08-31 12:20:12 -07:00
kernel bpf: fix control-flow graph checking in privileged mode 2023-11-28 17:19:50 +00:00
lib lib/generic-radix-tree.c: Don't overflow in peek() 2023-11-28 17:19:35 +00:00
LICENSES LICENSES: Add the copyleft-next-0.3.1 license 2022-11-08 15:44:01 +01:00
mm vfs: fix readahead(2) on block devices 2023-11-20 11:58:52 +01:00
net netfilter: nf_tables: bogus ENOENT when destroying element which does not exist 2023-11-28 17:19:52 +00:00
rust rust: docs: fix logo replacement 2023-10-19 16:40:00 +02:00
samples samples/bpf: syscall_tp_user: Fix array out-of-bound access 2023-11-28 17:19:48 +00:00
scripts gcc-plugins: randstruct: Only warn about true flexible arrays 2023-11-28 17:19:49 +00:00
security apparmor: fix invalid reference on profile->disconnected 2023-11-20 11:59:24 +01:00
sound ALSA: hda/realtek: Add quirk for ASUS UX7602ZM 2023-11-28 17:19:47 +00:00
tools bpf: fix control-flow graph checking in privileged mode 2023-11-28 17:19:50 +00:00
usr initramfs: Encode dependency on KBUILD_BUILD_TIMESTAMP 2023-06-06 17:54:49 +09:00
virt ARM: 2023-09-07 13:52:20 -07:00
.clang-format iommu: Add for_each_group_device() 2023-05-23 08:15:51 +02:00
.cocciconfig
.get_maintainer.ignore
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore kbuild: rpm-pkg: rename binkernel.spec to kernel.spec 2023-07-25 00:59:33 +09:00
.mailmap 20 hotfixes. 12 are cc:stable and the remainder address post-6.5 issues 2023-10-24 09:52:16 -10:00
.rustfmt.toml rust: add .rustfmt.toml 2022-09-28 09:02:20 +02:00
COPYING
CREDITS USB: Remove Wireless USB and UWB documentation 2023-08-09 14:17:32 +02:00
Kbuild Kbuild updates for v6.1 2022-10-10 12:00:45 -07:00
Kconfig
MAINTAINERS Char/Misc driver fixes for 6.6-final 2023-10-28 07:51:27 -10:00
Makefile Linux 6.6.2 2023-11-20 11:59:39 +01:00
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.