blk_classic tracing horribly broken

From: Jeff Moyer
Date: Thu Sep 22 2011 - 13:57:14 EST


Hi,

I've stared at the code for a while, and I've come up empty. Would
anyone care to take a stab at fixing this?

To reproduce:

mount -t debugfs none /sys/kernel/debug
cd /sys/kernel/debug/tracing
echo blk > current_tracer
echo 1 > events/block/enable
echo 1 > options/blk_classic
echo 1 > tracing_on

dd if=/dev/<device> of=/dev/null bs=1M count=1 iflag=direct
cat trace

This is what I see:

# tracer: blk
#
# DEV CPU TIMESTAMP PID ACT FLG
# | | | | | |
Unknown action 52
Unknown action 52
Unknown action bce
Unknown action 52
Unknown action 52
Unknown action 52
Unknown action 52
Unknown action 52
Unknown action 52
Unknown action 0
Unknown action 0
Unknown action 0
Unknown action 0
Unknown action 0
Unknown action 0
Unknown action 0
Unknown action 0
Unknown action 0
Unknown action 0
Unknown action 0
Unknown action 0
Unknown action 0
0,0 2 110.941937315 2584 F R [pgrep]
Unknown action 52
Unknown action 52
Unknown action 231
Unknown action 0
Unknown action 0
Unknown action 0
Unknown action 0
0,0 0 110.949383287 2584 F R [pgrep]
Unknown action 52
Unknown action 52
Unknown action 7fd1
Unknown action 0
Unknown action 0
Unknown action 0
Unknown action 0
0,0 3 110.984565328 2581 F R [ps]
Unknown action 52
Unknown action 52
Unknown action 5ad1
Unknown action 0
Unknown action 0
Unknown action 0
Unknown action 0
0,0 3 111.003843579 2581 F R [ps]
Unknown action 52
Unknown action 52
Unknown action 7551
Unknown action 0
Unknown action 0
Unknown action 0
Unknown action 0

Cheers,
Jeff
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