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Commit 1fd6a708 authored by Stefan Raspl's avatar Stefan Raspl Committed by Paolo Bonzini
Browse files

tools/kvm_stat: fix debugfs handling 



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: default avatarStefan Raspl <raspl@linux.vnet.ibm.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 1cd8bfb1

tools/kvm/kvm_stat/kvm_stat

+26 −14
Original line number Original line Diff line number Diff line
@@ -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)