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Full Discussion: Signals and semaphores
Top Forums Programming Signals and semaphores Post 302450355 by Corona688 on Thursday 2nd of September 2010 11:42:11 AM
Old 09-02-2010
Quote:
Originally Posted by achenle
I don't think sem_wait() is async-signal safe.
Correct. The only IPC that is, is sem_post. You might be able to create a more signal-safe arrangement wherein the interrupt handler only posts and the thread only waits.

Also, it's a good idea to check the return value of these things. In your current implementation sem_wait and sem_post are probably failing and returning EINTR at least sometimes, which will cause your semaphore to be off by one and lock the program solid.
 

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LEARN ABOUT FREEBSD

wake

WAKE(8) 						    BSD System Manager's Manual 						   WAKE(8)

NAME

     wake -- send Wake on LAN frames to hosts on a local Ethernet network

SYNOPSIS

     wake [interface] lladdr [lladdr ...]

DESCRIPTION

     The wake program is used to send Wake on LAN (WoL) frames over a local Ethernet network to one or more hosts using their link layer (hard-
     ware) addresses.  WoL functionality is generally enabled in a machine's BIOS and can be used to power on machines from a remote system with-
     out having physical access to them.

     interface is an Ethernet interface of the local machine and is used to send the Wake on LAN frames over it.  If there is only one Ethernet
     device available that is up and running, then the interface argument can be omitted.  lladdr is the link layer address of the remote machine.
     This can be specified as the actual hardware address (six hexadecimal numbers separated by colons) or as a hostname entry in /etc/ethers.
     wake accepts multiple lladdr addresses.  Link layer addresses can be determined and set using ifconfig(8).

FILES

     /etc/ethers  Ethernet host name data base.

SEE ALSO

     ethers(5), ifconfig(8)

AUTHORS

     wake was written by Marc Balmer <marc@msys.ch>.

BSD
								 December 27, 2009							       BSD
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