locking mutex (phtread_t type) in a signal handler function (installed by function signal()) for Linux. It seems that if the mutex has been previously locked by another thread outside the signal handler function and then the signal handler function tries to lock it, the whole process hangs.
View 5 RepliesI am doing some Linux kernel programming for my research project. I need to record the timestamp (by using cpuid and rdtsc) when an interrupt handler (top half) is first invoked. Due to the time critical nature of the problem itself, I have to do the timestamping inside the interrupt handler itself (the first operation when the handler is called). However, I understand that tasks that are not so time critical should be deferred to a tasklet function (bottom half) for processing because other interrupts are disabled in a (top-half) interrupt handler. I am currently out of idea on how I can pass the timestamp information that I have obtained in the interrupt handler to the corresponding tasklet function.
View 2 Replies View RelatedIs it possible to connect a signal handler to a variable?So when the variable changes the signal handler is called.I have a vector containing strings which i want to parse when there are one or more available strings in the vector
View 3 Replies View RelatedBasically I'm intending to write serial RX signal handler.Application receives defined packages of data over serial which contains header and payload. Handler should analyse incoming stream and upon detection of header (header is 6B in length) switches to receive payload of length defined in header, then after receiving full message packs it and sends to application for handling.Problem I'm facing is that at random moments in signal I receive errors that "Resource temporarily unavailable" while reading from ttyOx device and I see that sometimes I miss incoming data.Also is it possible that if while I'm handling signal one more signal arrives and it is started to be handled parallel? If it is, what are the ways to prevent it? So I would be sure that no more signals will fire on same peripheral until I will finish handling what I have on my hands now.
Serial open and init:
Code: Select allint open_port(int port_nr) {
int fd; /* File descriptor for the port */
switch (port_nr) {
case 1:
fd = open("/dev/ttyO1", O_RDWR | O_NOCTTY | O_NDELAY);
break;
[code]....
I'm new to Unix and every signal handler algorithm I've seen is more or less a copy of what I'm trying to do.[URL] designing a signal handler with sigwait in UNIX?
View 1 Replies View RelatedI am using Debian linux. I have 100 timers running. If a timer expired which will generate a signal and it was mapped to a same function handler. All the timers are mapped to one function handler. The problem is if the timer expires one at a time, the function handler called at a time. But if the 2 timers expires at a time, the function handler is called one time only instead 2 times. Is it possible to invoke the function handler as many times based on timer expirary happens simultaneoulsy?
View 14 Replies View RelatedI'm trying to create a signal handler thread to handle SIGALRM signals. The main thread calls the following function before creating any other threads
Code:
pthread_t Timer::Init(long _clock_interval_musec)
{
// Set interval.
clock_interval = _clock_interval_musec;
// This is called while in a single threaded environment.
[code]....
clock_interval is 50.
Is the timer not firing? Did I not set my interval correctly? Did I not proper block the signals ensuring the that the default handler would not take care of them?
I am wondering if pthread could make that a single thread keeps the "mutex" all the time if the time it remains unlocked is very small.
thread1
{
while (1)
{
lock; do_task(); unlock();
[code]...
I experiment the thread2 never getting access to the mutex and never printing the nice message. I would expect that once thread2 calls "lock", it would get the mutex as soon as thread1 calls unlock() but it does not seem to be the case. If I add a sleep of some microseconds (100) in thread1 after unlocking the mutex, it solves the problem.
Does anyone know if this behaviour is normal? Is there a way to configure my mutex so that thread2 receives it when unlocked?I use
pthread_mutexattr_settype(&att, PTHREAD_MUTEX_RECURSIVE_NP);
pthread_mutex_init(&handle, &att);
to create my mutex. I am running ubuntu 9.04
I am working on an issue in mishandling of mutex. A process was holding onto to a valid mutex for running, within this routine, it created a local mutex variable, copied the content of the valid mutex into this local mutex variable, freed the valid mutex, then used the address of the local mutex variable as the parameter to functions pthread_mutex_unlock() and pthread_mutex_destroy(). It was observed that CPU load 100% with scheduler staying in a loop. The program was halted. I try to seek an explanation to the relation between the CPU load and mutex mishandling in this scenario. I also hope some one will share the experience how this bug might manifest into problems on other platforms.
View 3 Replies View RelatedI am getting following assertion in my application:
pthread_mutex_lock.c:275: __pthread_mutex_lock: Assertion `(e) != 35 || (kind != PTHREAD_MUTEX_ERRORCHECK_NP && kind != PTHREAD_MUTEX_RECURSIVE_NP)' failed.
all my mutexes are of type PTHREAD_MUTEX_RECURSIVE and as per all the man pages/tutorials, EDEADLK error is to be returned for mutex of type PTHREAD_MUTEX_ERRORCHECK ONLY.I really should not be hitting this assertion.Would some kinda weird memory corruption be causing this? Or is there something more to it that I am not aware of.I am using linux kernel 2.6.2, glibc 2.5 on PPC.
If multiple threads operate on a single shared resource, we can lock it using pthread_mutex_lock. Uptill that it is fine, but why again pthread_cond_wait?
int shared=0; // global
.
.
// Thread 1
pthread_mutex_lock(&mutex);
shared=1;
pthread_mutex_unlock(&mutex);
When thread1 invokes the mutex lock, no other threads can access it in parallel. So why again and what for we use, pthread_cond_wait( ).
Code:
#include <iostream>
using namespace std;
[code]...
I have written a Linux kernel module (in Linux 2.4, Red Hat 9) which does the followings: It takes srcIP, sourceport, destIP, destport and loadvalue as command line arguments. If configured load value is greater than 1, it creates different channels (i.e. No of UDP channels created equals to configured load value), assign different source port and destination port to different channels and send UDP datagram in different channels. Say for example the configured parameters are as follows srcIP=10.17.17.43 destIP= 10.17.17.44 sourceport=10000 destport= 20000 loadvalue=2.
Then it creates two UDP different channels and transmits UDP packets (in every 20 milliseconds) to destination IP address (i.e., 10.17.17.44) with source port 10000, destination port 20000 in one channel and source port 10002, destination port 20000 in another channel. When I configure to pass ?loadvalue=500? and run the module, I get the below kernel panic message in system log file (i.e., var/log/messages) 0>Kernel panic: Aiee, killing interrupt handler! In interrupt handler - not syncing. Running the same linux kernel module ,in 1000 loadvalue, I get this message, eth0: Out-of-sync dirty pointer, 49937 vs. 49954 in text console. I am unable to catch the root cause of these problems and how will I solve these?
Is it possible to handle multiple signals in just one handler? I only know singal() catches one signal at a time
View 2 Replies View RelatedI am going to write two or more programs that will take control of the same resources on Linux. What are the common methods/functions that can do locks/synchronizations in C?
View 1 Replies View RelatedI want to declare a function in a function, but had no success till now, see the error code below and visit the project at sourceforge
[Code]...
I want that I click with the mouse on the video, it paused.I notice that there is "BaconVideoWidget" which I guess is the video rendering widget but it don't have signal named "clicked":
Code:
vd = totem_object.get_video_widget()
vd.connect("clicked", vd.hide)
[code]....
I looked on the net for such function or example and didin't find anything, thus after having made one i guess it would be legitimate to drop it to see what others thinks of it.
#!/bin/bash
addelementtoarray()
{
local arrayname=$1
[code]....
If I have two threads working on the same array but on different sections of the array, can they both write and read from it without locks and not have any sort of problem? If they only use completely different parts of the array always without affecting the other part?
View 3 Replies View RelatedI have a linked list that two threads work on simultainiousley.The first thread is adding elements to end the linked list while the second is removing them from the front. Can this be done without a lock on the linked list head when elements are beingadded/removed?
I think this lock is causing a performance hit to my application. If there isnt any safe way without it then thats fine but just thought I would check.The first thread uses this fuction to add elements to the list. Full source here. [URL]
Code:
/* Lets add the new packet to the queue. */
pthread_mutex_lock(&workers[queuenum].queue.lock); // Grab lock on queue.
if (workers[queuenum].queue.qlen == 0){ // Check if any packets are in the queue.
[code]...
fit a surface i.e. W(x,y) using svdfit() provided by "Numerical Recipes in C". svdfit() is written for curve fitting and not for surface fitting.But one can use svdfit(), as claimed by authors of NR book, to do surface fitting. On page 680 of NR book, authors have given a hint on how to use svdfit() for fitting a surface. But I have not understood it.This link may be helpful (Chapter 15 th is relevant here.):[URL]This is my problem:
Code:
I have a set of 100 numbers. I want to fit a 2-Dimensional function W(x,y) to these numbers.
[code]....
I'm doing the shell history audit logging using syslog to gather the command history. I'm using this well publicized method using trap and logger:
declare -r REAL_LOGNAME=`/usr/bin/who am i | cut -d" " -f1`
function log2syslog {
declare command
command=`fc -ln -0`
logger -p local1.notice -t bash -i ": $REAL_LOGNAME as $LOGNAME :$command"
}
trap log2syslog DEBUG TERM
The problem is that the trap on DEBUG will catch the next to last command executed (by virtue of the "fc" command) which is not the current command executed. TERM will catch that "next to last" command on exit, thus completing the logging of each command executed during that session.
However, CTL+D doesn't seem to emit a SIGTERM signal. What signal is actually being emitted and can it be trapped? I guess another question would be whether there is a way to trap history after command line execution? Moving to Bash 4.1 isn't possible in our "supported" multi-platform environment
I have created a pthread, and installed a signal handler inside that, same way as we do in main( ) function. The thread's signal handler is a separate function. Surprisingly, it is not working, that is the thread's signal handler is not able to catch signals. Here is the code:
Code: #include <unistd.h>
#include <sys/types.h>
#include <stdio.h>
#include <signal.h>
typedef struct data
[Code]...
I have a Socket library, written in C++, in which the method used to send data never has the opportunity to handle an errno of SIGPIPE. Thus I thought perhaps I should setup a signal handler to receive the signal, but this too is not being called.Is there something that I am missing or doing that is completely wrong? Below is the relevant code. Note that a SIGPIPE signal is generated when the Server is unable to send data to the Client (e.g. the client has terminated).Server code:
Code:
#include <TCPServerSocket.hpp>
#include <string>
[code]...
I have a signal handler in my tool, which is registered and used between some particular interval (i am using timer). Now this signal handler should NOT allow any other handler to be registered or invoked after this handler is once registered. Is there any way to accomplish this?
[code]...
I am writing a bash script where I need standard Input should be saved in a file and should be terminated by passing CTRL+D signal. Any clue how can I do that in bash script.
e.g.
Enter one line at a time
Press CTRL+D to finish
But unable to catch the SIGTERM signal if I do shutdown, as man pages says shutdown genrates the SIGTERM and SIGKILL signals, but we cant handle the SIGKILL signal. My code is working fine if I genrate the SIGTERM signal by Kill command, and also for SIGINT signgal genrated from the CTRL+c key.
Here is my code:
/* Example of using sigaction() to setup a signal handler with 3 arguments
* including siginfo_t.
*/
#include <stdio.h>
#include <unistd.h>
#include <signal.h>
#include <string.h>
[Code]...
I was trying to program using fork(). The objective of this code is to
1. I am activating a process A - SubSuctionMotors.
2. Process A is going to stop with either of this condition
a) Switch is activated - swret=1
b) Time allowed has expired
3. Stop the process A.
[Code]...
1. We purposely force the switch to be inactive to test the child process (timer), whether after 2 seconds the motor stop. It turns out to be successful in first few attempts. After some while, the program hang, nothing is executed anymore and the program is not exit or terminated. What can cause the program to hang?
2. We tried to stop motor by switch activation (if the switch is to be successfully activated, the time it takes will always be shorter than the timer allowed time). However, the program did not seems like noticing the switch has been activated, and it just stop the motor according to timer. Why it behave this way?
#!/bin/sh
trap "echo Haha" SIGUSER1
echo "asit"
count=1
while [ $count -le 10 ]
do
echo "Loop #$count"
sleep 10
count=$[ $count + 1 ]
done
echo "This is the end"
Why this is showing following error?
trap: 3: SIGUSER1: bad trap
I'm just beginning to program with GTK+, and I'm facing this issue: I want to inhibit a signal emission inside one and only one function. I've down cut my code into the smallest example I can to show you what I want to do:The "Emitter" contains a "GtkSpinBox" and it relays the "value-changed" signal, it's header:
Code:
#ifndef EMITTER_H
#define EMITTER_H
[code]....