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arm_mpam: Stop using uninitialized variables in __ris_msmon_read()

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Dan has reported two uses of uninitialized variables in __ris_msmon_read().
If an unknown monitor type is encountered then the local variable, now, is
used uninitialized. Fix this by returning early on error. If a non-mbwu
monitor is being read then the local variable, overflow, is not initialized
but still read. Initialize it to false as overflow is not relevant for csu
monitors.

Fixes: 823e7c3712c5 ("arm_mpam: Add mpam_msmon_read() to read monitor value")
Fixes: 9e5afb7c3283 ("arm_mpam: Use long MBWU counters if supported")
Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Closes: https://lore.kernel.org/r/202512091519.RBwiJcSq-lkp@intel.com/
Closes: https://lore.kernel.org/r/202512100547.N7QPYgfb-lkp@intel.com/
Signed-off-by: Ben Horgan <ben.horgan@arm.com>
Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
This commit is contained in:
Ben Horgan 2025-12-19 18:11:03 +00:00 committed by Catalin Marinas
parent dd4d71f587
commit c2803bd580
1 changed files with 4 additions and 3 deletions
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7
drivers/resctrl/mpam_devices.c
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@ -1072,7 +1072,7 @@ static void __ris_msmon_read(void *arg)
u64 now;
bool nrdy = false;
bool config_mismatch;
bool overflow;
bool overflow = false;
struct mon_read *m = arg;
struct mon_cfg *ctx = m->ctx;
bool reset_on_next_read = false;
@ -1176,10 +1176,11 @@ static void __ris_msmon_read(void *arg)
}
mpam_mon_sel_unlock(msc);
if (nrdy) {
if (nrdy)
m->err = -EBUSY;
if (m->err)
return;
}
*m->val += now;
}