December 2002
Intermediate to advanced
784 pages
27h 7m
English
Content preview from Understanding the Linux Kernel, Second EditionBecome an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.
Generating a Signal
When
a signal is sent to a process, either from the kernel or from another
process, the kernel generates it by invoking the
send_sig_info( ), send_sig( ),
force_sig( ), or force_sig_info( ) functions. These accomplish the first phase of signal
handling described earlier in Section 10.1, updating the process
descriptor as needed. They do not directly perform the second phase
of delivering the signal but, depending on the type of signal and the
state of the process, may wake up the process and force it to receive
the signal.
The send_sig_info( ) and send_sig( ) Functions
The send_sig_info( ) function acts on three parameters:
-
sig The signal number.
-
info Either the address of a
siginfo_ttable or one of two special values. 0 means that the signal has been sent by a User Mode process, while 1 means that it has been sent by the kernel.-
t A pointer to the descriptor of the destination process.
The send_sig_info( ) function starts by checking
whether the parameters are correct:
if (sig < 0 || sig > 64)
return -EINVAL;The function then checks if the signal is being sent by a User Mode
process. This occurs when info is equal to 0 or
when the si_code field of the
siginfo_t table is negative or 0 (positive values
of this field mean that the signal was sent by some kernel function):
if ((!info || ((unsigned long)info != 1 && (info->si_code <=0))) && ((sig != SIGCONT) || (current->session != t->session)) && (current->euid ^ t->suid) && (current->euid ^ t->uid) && (current->uid ...
Become an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
and much more.
Read now
Unlock full access
More than 5,000 organizations count on O’Reilly
O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.