Re: [PATCH v27 04/12] LRNG - add switchable DRNG support

Am Samstag, 11. Januar 2020, 08:09:50 CET schrieb kbuild test robot:

Hi,

Hi "Stephan,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on char-misc/char-misc-testing]
[also build test WARNING on cryptodev/master crypto/master v5.5-rc5
next-20200110] [if your patch is applied to the wrong git tree, please drop
us a note to help improve the system. BTW, we also suggest to use '--base'
option to specify the base tree in git format-patch, please see
https://stackoverflow.com/a/37406982]

url:   
https://github.com/0day-ci/linux/commits/Stephan-M-ller/dev-random-a-new-ap
proach-with-full-SP800-90B/20200110-084934 base:  
https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc.git
68faa679b8be1a74e6663c21c3a9d25d32f1c079 reproduce:
        # apt-get install sparse
        # sparse version: v0.6.1-129-g341daf20-dirty
        make ARCH=x86_64 allmodconfig
        make C=1 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__'

If you fix the issue, kindly add following tag
Reported-by: kbuild test robot <redacted>


sparse warnings: (new ones prefixed by >>)

quoted

quoted

drivers/char/lrng/lrng_internal.h:239:39: sparse: sparse: context
imbalance in 'lrng_drng_switch' - unexpected unlock

vim +/lrng_drng_switch +239 drivers/char/lrng/lrng_internal.h

58c283819a1e87 Stephan Müller 2020-01-09  233
58c283819a1e87 Stephan Müller 2020-01-09  234  /* Unlock the DRNG */
58c283819a1e87 Stephan Müller 2020-01-09  235  static __always_inline void
lrng_drng_unlock(struct lrng_drng *drng, 58c283819a1e87 Stephan Müller
2020-01-09  236  					     unsigned long *flags) 

58c283819a1e87 Stephan

Müller 2020-01-09  237  {
58c283819a1e87 Stephan Müller 2020-01-09  238  	if
(lrng_drng_is_atomic(drng)) 58c283819a1e87 Stephan Müller 2020-01-09 @239 
		spin_unlock_irqrestore(&drng->spin_lock, *flags); 58c283819a1e87 

Stephan

Müller 2020-01-09  240  	else
58c283819a1e87 Stephan Müller 2020-01-09  241  		mutex_unlock(&drng-
lock);
58c283819a1e87 Stephan Müller 2020-01-09  242  }
58c283819a1e87 Stephan Müller 2020-01-09  243

:::::: The code at line 239 was first introduced by commit
:::::: 58c283819a1e879bc2e30d05720285f9709f7f6d Linux Random Number
:::::: Generator
:::::: 
:::::: TO: Stephan Müller [off-list ref]
:::::: CC: 0day robot [off-list ref]

---
0-DAY kernel test infrastructure                 Open Source Technology
Center https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org Intel
Corporation

After analyzing the issue a bit more, it seems that I have to remove 
"unlikely" from lrng_drng_lock which seems to cause additional grief
with sparse. Note, sparse will still report a lock context imbalance as it
used to since we indeed have two lock context as documented in
lrng_drng_switch.

Ciao
Stephan