drivers/gpu/drm/i915/intel_uncore.c:2009 __intel_wait_for_register_fw() error: uninitialized symbol 'reg_value'.

From: kernel test robot
Date: Fri Aug 07 2020 - 16:35:36 EST

tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head: 5631c5e0eb9035d92ceb20fcd9cdb7779a3f5cc7
commit: 3f649ab728cda8038259d8f14492fe400fbab911 treewide: Remove uninitialized_var() usage
date: 3 weeks ago
config: i386-randconfig-m021-20200807 (attached as .config)
compiler: gcc-9 (Debian 9.3.0-15) 9.3.0

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@xxxxxxxxx>

New smatch warnings:
drivers/gpu/drm/i915/intel_uncore.c:2009 __intel_wait_for_register_fw() error: uninitialized symbol 'reg_value'.
drivers/gpu/drm/i915/gt/intel_lrc.c:1134 __unwind_incomplete_requests() error: uninitialized symbol 'pl'.

Old smatch warnings:
drivers/gpu/drm/i915/gt/intel_lrc.c:5668 intel_execlists_create_virtual() warn: assigning (-2) to unsigned variable 've->base.instance'
drivers/gpu/drm/i915/gt/intel_lrc.c:5669 intel_execlists_create_virtual() warn: assigning (-2) to unsigned variable 've->base.uabi_instance'

vim +/reg_value +2009 drivers/gpu/drm/i915/intel_uncore.c

907b28c56ea4062 Chris Wilson 2013-07-19 1959
1758b90e38f53b9 Chris Wilson 2016-06-30 1960 /**
1d1a9774e404141 Michal Wajdeczko 2017-04-07 1961 * __intel_wait_for_register_fw - wait until register matches expected state
d2d551c06f81775 Daniele Ceraolo Spurio 2019-03-25 1962 * @uncore: the struct intel_uncore
1758b90e38f53b9 Chris Wilson 2016-06-30 1963 * @reg: the register to read
1758b90e38f53b9 Chris Wilson 2016-06-30 1964 * @mask: mask to apply to register value
1758b90e38f53b9 Chris Wilson 2016-06-30 1965 * @value: expected value
1d1a9774e404141 Michal Wajdeczko 2017-04-07 1966 * @fast_timeout_us: fast timeout in microsecond for atomic/tight wait
1d1a9774e404141 Michal Wajdeczko 2017-04-07 1967 * @slow_timeout_ms: slow timeout in millisecond
1d1a9774e404141 Michal Wajdeczko 2017-04-07 1968 * @out_value: optional placeholder to hold registry value
1758b90e38f53b9 Chris Wilson 2016-06-30 1969 *
1758b90e38f53b9 Chris Wilson 2016-06-30 1970 * This routine waits until the target register @reg contains the expected
3d466cd67e85fe1 Daniel Vetter 2016-07-15 1971 * @value after applying the @mask, i.e. it waits until ::
3d466cd67e85fe1 Daniel Vetter 2016-07-15 1972 *
3d466cd67e85fe1 Daniel Vetter 2016-07-15 1973 * (I915_READ_FW(reg) & mask) == value
3d466cd67e85fe1 Daniel Vetter 2016-07-15 1974 *
1d1a9774e404141 Michal Wajdeczko 2017-04-07 1975 * Otherwise, the wait will timeout after @slow_timeout_ms milliseconds.
6976e74b5fa1243 Michal Wajdeczko 2017-04-10 1976 * For atomic context @slow_timeout_ms must be zero and @fast_timeout_us
84d84cb7e20d3d2 Chris Wilson 2017-04-11 1977 * must be not larger than 20,0000 microseconds.
1758b90e38f53b9 Chris Wilson 2016-06-30 1978 *
1758b90e38f53b9 Chris Wilson 2016-06-30 1979 * Note that this routine assumes the caller holds forcewake asserted, it is
1758b90e38f53b9 Chris Wilson 2016-06-30 1980 * not suitable for very long waits. See intel_wait_for_register() if you
1758b90e38f53b9 Chris Wilson 2016-06-30 1981 * wish to wait without holding forcewake for the duration (i.e. you expect
1758b90e38f53b9 Chris Wilson 2016-06-30 1982 * the wait to be slow).
1758b90e38f53b9 Chris Wilson 2016-06-30 1983 *
e4661f144497f58 Michal Wajdeczko 2019-08-02 1984 * Return: 0 if the register matches the desired condition, or -ETIMEDOUT.
1758b90e38f53b9 Chris Wilson 2016-06-30 1985 */
d2d551c06f81775 Daniele Ceraolo Spurio 2019-03-25 1986 int __intel_wait_for_register_fw(struct intel_uncore *uncore,
1758b90e38f53b9 Chris Wilson 2016-06-30 1987 i915_reg_t reg,
3fc7d86b3268af9 Michal Wajdeczko 2017-04-10 1988 u32 mask,
3fc7d86b3268af9 Michal Wajdeczko 2017-04-10 1989 u32 value,
3fc7d86b3268af9 Michal Wajdeczko 2017-04-10 1990 unsigned int fast_timeout_us,
3fc7d86b3268af9 Michal Wajdeczko 2017-04-10 1991 unsigned int slow_timeout_ms,
1d1a9774e404141 Michal Wajdeczko 2017-04-07 1992 u32 *out_value)
1758b90e38f53b9 Chris Wilson 2016-06-30 1993 {
3f649ab728cda80 Kees Cook 2020-06-03 1994 u32 reg_value;
d2d551c06f81775 Daniele Ceraolo Spurio 2019-03-25 1995 #define done (((reg_value = intel_uncore_read_fw(uncore, reg)) & mask) == value)
1d1a9774e404141 Michal Wajdeczko 2017-04-07 1996 int ret;
1d1a9774e404141 Michal Wajdeczko 2017-04-07 1997
6976e74b5fa1243 Michal Wajdeczko 2017-04-10 1998 /* Catch any overuse of this function */
84d84cb7e20d3d2 Chris Wilson 2017-04-11 1999 might_sleep_if(slow_timeout_ms);
84d84cb7e20d3d2 Chris Wilson 2017-04-11 2000 GEM_BUG_ON(fast_timeout_us > 20000);
6976e74b5fa1243 Michal Wajdeczko 2017-04-10 2001
84d84cb7e20d3d2 Chris Wilson 2017-04-11 2002 ret = -ETIMEDOUT;
84d84cb7e20d3d2 Chris Wilson 2017-04-11 2003 if (fast_timeout_us && fast_timeout_us <= 20000)
1d1a9774e404141 Michal Wajdeczko 2017-04-07 2004 ret = _wait_for_atomic(done, fast_timeout_us, 0);
ff26ffa8ee267dc Daniel Vetter 2017-05-10 2005 if (ret && slow_timeout_ms)
1d1a9774e404141 Michal Wajdeczko 2017-04-07 2006 ret = wait_for(done, slow_timeout_ms);
84d84cb7e20d3d2 Chris Wilson 2017-04-11 2007
1d1a9774e404141 Michal Wajdeczko 2017-04-07 2008 if (out_value)
1d1a9774e404141 Michal Wajdeczko 2017-04-07 @2009 *out_value = reg_value;
84d84cb7e20d3d2 Chris Wilson 2017-04-11 2010
1758b90e38f53b9 Chris Wilson 2016-06-30 2011 return ret;
1758b90e38f53b9 Chris Wilson 2016-06-30 2012 #undef done
1758b90e38f53b9 Chris Wilson 2016-06-30 2013 }
1758b90e38f53b9 Chris Wilson 2016-06-30 2014

:::::: The code at line 2009 was first introduced by commit
:::::: 1d1a9774e40414148ecebbdb713746bfb6f9a561 drm/i915: Extend intel_wait_for_register_fw() with fast timeout

:::::: TO: Michal Wajdeczko <michal.wajdeczko@xxxxxxxxx>
:::::: CC: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>

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