RCU_READ_LOCK_BH_HEL(9) Driver Basics RCU_READ_LOCK_BH_HEL(9)NAME
rcu_read_lock_bh_held - might we be in RCU-bh read-side critical section?
Check for bottom half being disabled, which covers both the CONFIG_PROVE_RCU and not cases. Note that if someone uses rcu_read_lock_bh, but
then later enables BH, lockdep (if enabled) will show the situation. This is useful for debug checks in functions that require that they be
called within an RCU read-side critical section.
Check debug_lockdep_rcu_enabled to prevent false positives during boot.
Note that rcu_read_lock is disallowed if the CPU is either idle or offline from an RCU perspective, so check for those as well.
COPYRIGHT Kernel Hackers Manual 3.10 June 2014 RCU_READ_LOCK_BH_HEL(9)
Check Out this Related Man Page
CRITICAL_ENTER(9) BSD Kernel Developer's Manual CRITICAL_ENTER(9)NAME
critical_enter, critical_exit -- enter and exit a critical region
These functions are used to prevent preemption in a critical region of code. All that is guaranteed is that the thread currently executing
on a CPU will not be preempted. Specifically, a thread in a critical region will not migrate to another CPU while it is in a critical
region. The current CPU may still trigger faults and exceptions during a critical section; however, these faults are usually fatal.
The critical_enter() and critical_exit() functions manage a per-thread counter to handle nested critical sections. If a thread is made
runnable that would normally preempt the current thread while the current thread is in a critical section, then the preemption will be
deferred until the current thread exits the outermost critical section.
Note that these functions are not required to provide any inter-CPU synchronization, data protection, or memory ordering guarantees and thus
should not be used to protect shared data structures.
These functions should be used with care as an infinite loop within a critical region will deadlock the CPU. Also, they should not be inter-
locked with operations on mutexes, sx locks, semaphores, or other synchronization primitives. One exception to this is that spin mutexes
include a critical section, so in certain cases critical sections may be interlocked with spin mutexes.
These functions were introduced in FreeBSD 5.0.
BSD October 5, 2005 BSD
I know the following questions are noobish questions but I am asking them because I am confused about the basics of history behind UNIX and LINUX.
Ok onto business, my questions are-:
Was/Is UNIX ever an open source operating system ?
If UNIX was... (21 Replies)
Hello and thanks in advance for any help anyone can offer me
I'm trying to learn the find command and thought I was understanding it... Apparently I was wrong. I was doing compound searches and I started getting weird results with the -size test. I was trying to do a search on a 1G file owned by... (14 Replies)
i have installed quota on my centos 7 machine and its what im after (setting size limit on users, so they cant fill the hard drive)
i want to now make this part of my create user script for my sftp server so i want to do a echo and a read command so i capture the limit they enter... (0 Replies)
I need to write a shell script which opens a file and increments the version(text) within the file every time the script runs. For example:
$ cat docker_file.yml
So, I would like... (6 Replies)
We use DB2 v10.5 and using DBArtisan tool
Can someone please guide how to convert digits to binary numbers using db2 feature.
Ex> for number 9 , binary should be 1001 ( 8+1)
Any help appreciated. Thanks (2 Replies)
how to using tar with exclude directory and compress it using tar.Z
i only know how to exclude dir only with this command below:
tar -cvf /varios/restore/test.tar -X excludefile.txt /jfma/test1/
how to compress it using 1 command?
Please use CODE tags as... (6 Replies)
Quite an obscure question I think.
We have a rebuild process for remote sites that allows us to PXE rebuild a till (actually a PC with a touch screen and various fancy bits) running CentOS. The current CentOS5 tills work just fine with a tar image restore and some personalisation. Sadly,... (4 Replies)
I had recently learnt a bit of Docker(which provides containerization process).
Here are some of my learning points from it.
Let us start first with very basic question:
What is Docker:
Docker is a platform for sysadmins and developers to DEPLOY, DEVELOP and RUN applications ... (7 Replies)
What is the point of this? Whenever I close my shell it appends to the history file without adding this. I have never seen it overwrite my history file.
# When the shell exits, append to the history file instead of overwriting it
shopt -s histappend (3 Replies)
Hello... And thanks in advance for any help anyone can offer me
I was trying to work out the differences between displaying modify, access, and change times with the 'ls' command. Everything seems in order when I look at files, but the access time on a directory doesn't seem to change when I... (4 Replies)
I am having an issue here with CentOS release 6.6 (Final) that shows all of the space used up, but I can't tell where the space went.
Seemingly I am using up 100%, according to
Filesystem Size Used Avail Use% Mounted on... (27 Replies)
I'm trying to use a bash script for a psych experiment that involves listening to sound files and responding. If I have something like the code below, how can I make sure that a key press is assigned to RESPONSE only after the second echo statement?
for i in 1 2 3; do
... (10 Replies)
After the success of the jq - tool for parsing and manipulating JSON-Data someone wrote a tool called yq, which aims to be the same for YAML, what jq is for JSON. Seems to work fine. I'll definitely give it a chance in future.
... (1 Reply)
I am very pleased to announce that Dave Munro (gull04) is joining the Moderation Team, after being a very valuable member of UNIX.com for 15+ years.
Dave is an IT Consultant with 30 years of experience this year, has worked in many of the industry vertical market segments and has... (6 Replies)