diff options
| author | Yijie Yang <yijie.yang@oss.qualcomm.com> | 2026-08-11 16:46:47 +0800 |
|---|---|---|
| committer | Rob Herring (Arm) <robh@kernel.org> | 2026-08-15 15:46:52 -0500 |
| commit | e1c13aed4a1641550e8c9518c96f016e1d52d09b (patch) | |
| tree | 61c2297688373db165cc857b7c7adcb147a5c419 /Documentation/filesystems/locks.rst | |
| download | linux-stable-e1c13aed4a1641550e8c9518c96f016e1d52d09b.tar.gz linux-stable-e1c13aed4a1641550e8c9518c96f016e1d52d09b.zip | |
dt-bindings: interconnect: qcom-bwmon: Add Maili cpu-bwmon compatiblegrafted
Add the Qualcomm Maili SoC compatible string for the CPU bandwidth
monitor (BWMONv4). This falls back to the sdm845-bwmon compatible,
consistent with the existing pattern used by other recent SoCs such as
sm8750 and kaanapali.
Signed-off-by: Yijie Yang <yijie.yang@oss.qualcomm.com>
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@oss.qualcomm.com>
Reviewed-by: Jingyi Wang <jingyi.wang@oss.qualcomm.com>
Link: https://patch.msgid.link/20260811-bwmon-v2-1-80f7f150ab9e@oss.qualcomm.com
Signed-off-by: Rob Herring (Arm) <robh@kernel.org>
Diffstat (limited to 'Documentation/filesystems/locks.rst')
| -rw-r--r-- | Documentation/filesystems/locks.rst | 65 |
1 files changed, 65 insertions, 0 deletions
diff --git a/Documentation/filesystems/locks.rst b/Documentation/filesystems/locks.rst new file mode 100644 index 000000000..26429317d --- /dev/null +++ b/Documentation/filesystems/locks.rst @@ -0,0 +1,65 @@ +.. SPDX-License-Identifier: GPL-2.0 + +========================== +File Locking Release Notes +========================== + + Andy Walker <andy@lysaker.kvaerner.no> + + 12 May 1997 + + +1. What's New? +============== + +1.1 Broken Flock Emulation +-------------------------- + +The old flock(2) emulation in the kernel was swapped for proper BSD +compatible flock(2) support in the 1.3.x series of kernels. With the +release of the 2.1.x kernel series, support for the old emulation has +been totally removed, so that we don't need to carry this baggage +forever. + +This should not cause problems for anybody, since everybody using a +2.1.x kernel should have updated their C library to a suitable version +anyway (see the file "Documentation/process/changes.rst".) + +1.2 Allow Mixed Locks Again +--------------------------- + +1.2.1 Typical Problems - Sendmail +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ +Because sendmail was unable to use the old flock() emulation, many sendmail +installations use fcntl() instead of flock(). This is true of Slackware 3.0 +for example. This gave rise to some other subtle problems if sendmail was +configured to rebuild the alias file. Sendmail tried to lock the aliases.dir +file with fcntl() at the same time as the GDBM routines tried to lock this +file with flock(). With pre 1.3.96 kernels this could result in deadlocks that, +over time, or under a very heavy mail load, would eventually cause the kernel +to lock solid with deadlocked processes. + + +1.2.2 The Solution +^^^^^^^^^^^^^^^^^^ +The solution I have chosen, after much experimentation and discussion, +is to make flock() and fcntl() locks oblivious to each other. Both can +exists, and neither will have any effect on the other. + +I wanted the two lock styles to be cooperative, but there were so many +race and deadlock conditions that the current solution was the only +practical one. It puts us in the same position as, for example, SunOS +4.1.x and several other commercial Unices. The only OS's that support +cooperative flock()/fcntl() are those that emulate flock() using +fcntl(), with all the problems that implies. + + +1.3 Mandatory Locking As A Mount Option +--------------------------------------- + +Mandatory locking was prior to this release a general configuration option +that was valid for all mounted filesystems. This had a number of inherent +dangers, not the least of which was the ability to freeze an NFS server by +asking it to read a file for which a mandatory lock existed. + +Such option was dropped in Kernel v5.14. |
