Hi,
I am trying to log information from within the kernel with the use of a unix
socket (/dev/log).
My code is a kprobe handler, so while executing I am atomic and uninterrupted.
The crashes begin when I do stress tests against my module, so i.e. more than
50 logs per second.
The crash messages I get every time are different (from NULL reference, unable
to handle page request etc), so I suppose that something is overwritten and
this leads to the crash.
I don't want to post the code here because it ~100 LOC but these are my steps:
Initialization:
call sock_create_kern, with PF_UNIX, SOCK_DGRAM, 0 and the address of my
socket,
then I memset to 0 my sockaddr_un variable and then I set its sun_family
to PF_UNIX and copy the "/dev/log" string to sun_path
Logging:
I have the message that I want to log in variable called buffer and its
length in variable called message_length,
I set the msg_name of the msghdr to the address of my sockaddr_un variable,
than the msn_namelen to sizeof(sockadrr_un), the msg_iov to an iovec variable
which contains the buffer and the message_length values, msg_iovlen to 1 and
msg_control, msg_controllen to 0.
Then I set the fs to KERNEL_DS, call sock_sendmsg with parameters my
socket, the address of my msghdr and the message_length and then I restore the
fs that there was before setting it to KERNEL_DS.
Please note that my socket, sockadd_un and my buffer are static variables. Also
I always use the socket which is initialized once in the Initialization state
(function).
Do you see any "bad practice" or something that could lead to crashes when
stressing with a lot of messages the socket?
Thank you in advance!
Panos
--
http://www.cern.ch/psakkos
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