Revision 10f1d5d111e8aed46a0f1179faf9a3cf422f689e authored by Joe Thornber on 27 June 2014, 19:29:04 UTC, committed by Mike Snitzer on 10 July 2014, 20:44:14 UTC
There's a race condition between the atomic_dec_and_test(&io->count) in dec_count() and the waking of the sync_io() thread. If the thread is spuriously woken immediately after the decrement it may exit, making the on stack io struct invalid, yet the dec_count could still be using it. Fix this race by using a completion in sync_io() and dec_count(). Reported-by: Minfei Huang <huangminfei@ucloud.cn> Signed-off-by: Joe Thornber <thornber@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com> Acked-by: Mikulas Patocka <mpatocka@redhat.com> Cc: stable@vger.kernel.org
1 parent bf14299
decode_stacktrace.sh
#!/bin/bash
# (c) 2014, Sasha Levin <sasha.levin@oracle.com>
#set -x
if [[ $# != 2 ]]; then
echo "Usage:"
echo " $0 [vmlinux] [base path]"
exit 1
fi
vmlinux=$1
basepath=$2
declare -A cache
parse_symbol() {
# The structure of symbol at this point is:
# [name]+[offset]/[total length]
#
# For example:
# do_basic_setup+0x9c/0xbf
# Strip the symbol name so that we could look it up
local name=${symbol%+*}
# Use 'nm vmlinux' to figure out the base address of said symbol.
# It's actually faster to call it every time than to load it
# all into bash.
if [[ "${cache[$name]+isset}" == "isset" ]]; then
local base_addr=${cache[$name]}
else
local base_addr=$(nm "$vmlinux" | grep -i ' t ' | awk "/ $name\$/ {print \$1}" | head -n1)
cache["$name"]="$base_addr"
fi
# Let's start doing the math to get the exact address into the
# symbol. First, strip out the symbol total length.
local expr=${symbol%/*}
# Now, replace the symbol name with the base address we found
# before.
expr=${expr/$name/0x$base_addr}
# Evaluate it to find the actual address
expr=$((expr))
local address=$(printf "%x\n" "$expr")
# Pass it to addr2line to get filename and line number
# Could get more than one result
if [[ "${cache[$address]+isset}" == "isset" ]]; then
local code=${cache[$address]}
else
local code=$(addr2line -i -e "$vmlinux" "$address")
cache[$address]=$code
fi
# addr2line doesn't return a proper error code if it fails, so
# we detect it using the value it prints so that we could preserve
# the offset/size into the function and bail out
if [[ $code == "??:0" ]]; then
return
fi
# Strip out the base of the path
code=${code//$basepath/""}
# In the case of inlines, move everything to same line
code=${code//$'\n'/' '}
# Replace old address with pretty line numbers
symbol="$name ($code)"
}
decode_code() {
local scripts=`dirname "${BASH_SOURCE[0]}"`
echo "$1" | $scripts/decodecode
}
handle_line() {
local words
# Tokenize
read -a words <<<"$1"
# Remove hex numbers. Do it ourselves until it happens in the
# kernel
# We need to know the index of the last element before we
# remove elements because arrays are sparse
local last=$(( ${#words[@]} - 1 ))
for i in "${!words[@]}"; do
# Remove the address
if [[ ${words[$i]} =~ \[\<([^]]+)\>\] ]]; then
unset words[$i]
fi
# Format timestamps with tabs
if [[ ${words[$i]} == \[ && ${words[$i+1]} == *\] ]]; then
unset words[$i]
words[$i+1]=$(printf "[%13s\n" "${words[$i+1]}")
fi
done
# The symbol is the last element, process it
symbol=${words[$last]}
unset words[$last]
parse_symbol # modifies $symbol
# Add up the line number to the symbol
echo "${words[@]}" "$symbol"
}
while read line; do
# Let's see if we have an address in the line
if [[ $line =~ \[\<([^]]+)\>\] ]]; then
# Translate address to line numbers
handle_line "$line"
# Is it a code line?
elif [[ $line == *Code:* ]]; then
decode_code "$line"
else
# Nothing special in this line, show it as is
echo "$line"
fi
done
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