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tools/kvm_stat: fix debugfs handling

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Te checks for debugfs assumed that debugfs is always mounted at
/sys/kernel/debug - which is likely, but not guaranteed. This is addressed
by checking /proc/mounts for the actual location.
Furthermore, when debugfs was mounted, but the kvm module not loaded, a
misleading error pointing towards debugfs not present was given.
To reproduce,
(a) run kvm_stat with debugfs mounted at a place different from
    /sys/kernel/debug
(b) run kvm_stat with debugfs mounted but kvm module not loaded

Signed-off-by: Stefan Raspl <raspl@linux.vnet.ibm.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Stefan Raspl 2018-02-22 12:16:24 +01:00 committed by Paolo Bonzini
parent 1cd8bfb1ed
commit 1fd6a708c8
1 changed files with 26 additions and 14 deletions
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40
tools/kvm/kvm_stat/kvm_stat
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@ -331,9 +331,6 @@ class perf_event_attr(ctypes.Structure):
PERF_TYPE_TRACEPOINT = 2 PERF_TYPE_TRACEPOINT = 2
PERF_FORMAT_GROUP = 1 << 3 PERF_FORMAT_GROUP = 1 << 3
PATH_DEBUGFS_TRACING = '/sys/kernel/debug/tracing'
PATH_DEBUGFS_KVM = '/sys/kernel/debug/kvm'
class Group(object): class Group(object):
"""Represents a perf event group.""" """Represents a perf event group."""
@ -1544,17 +1541,6 @@ Press any other key to refresh statistics immediately.
def check_access(options): def check_access(options):
"""Exits if the current user can't access all needed directories.""" """Exits if the current user can't access all needed directories."""
if not os.path.exists('/sys/kernel/debug'):
sys.stderr.write('Please enable CONFIG_DEBUG_FS in your kernel.')
sys.exit(1)
if not os.path.exists(PATH_DEBUGFS_KVM):
sys.stderr.write("Please make sure, that debugfs is mounted and "
"readable by the current user:\n"
"('mount -t debugfs debugfs /sys/kernel/debug')\n"
"Also ensure, that the kvm modules are loaded.\n")
sys.exit(1)
if not os.path.exists(PATH_DEBUGFS_TRACING) and (options.tracepoints or if not os.path.exists(PATH_DEBUGFS_TRACING) and (options.tracepoints or
not options.debugfs): not options.debugfs):
sys.stderr.write("Please enable CONFIG_TRACING in your kernel " sys.stderr.write("Please enable CONFIG_TRACING in your kernel "
@ -1572,7 +1558,33 @@ def check_access(options):
return options return options
def assign_globals():
global PATH_DEBUGFS_KVM
global PATH_DEBUGFS_TRACING
debugfs = ''
for line in file('/proc/mounts'):
if line.split(' ')[0] == 'debugfs':
debugfs = line.split(' ')[1]
break
if debugfs == '':
sys.stderr.write("Please make sure that CONFIG_DEBUG_FS is enabled in "
"your kernel, mounted and\nreadable by the current "
"user:\n"
"('mount -t debugfs debugfs /sys/kernel/debug')\n")
sys.exit(1)
PATH_DEBUGFS_KVM = os.path.join(debugfs, 'kvm')
PATH_DEBUGFS_TRACING = os.path.join(debugfs, 'tracing')
if not os.path.exists(PATH_DEBUGFS_KVM):
sys.stderr.write("Please make sure that CONFIG_KVM is enabled in "
"your kernel and that the modules are loaded.\n")
sys.exit(1)
def main(): def main():
assign_globals()
options = get_options() options = get_options()
options = check_access(options) options = check_access(options)