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Feature #7465

closed

Explicitly specify proper memory allocation for interfaces of well known categories

Added by Evgeny Novikov over 8 years ago. Updated about 8 years ago.

Status:
Closed
Priority:
Urgent
Assignee:
Category:
Environment models
Target version:
-
Start date:
08/12/2016
Due date:
% Done:

0%

Estimated time:
Published in build:
abe8578

Description

We know that this should be done at least for callbacks of platform_driver. This should make it possible to properly find target bug c822fb57ba12~/drivers/spi/spi-pxa2xx-platform.ko/linux:clk1.

Actions #1

Updated by Ilja Zakharov over 8 years ago

  • Status changed from New to Resolved

Done in 'emg-alloc' branch.

For all user specified interfaces corresponding memory allocations now are correct allocations with proper sizeof if corresponding EMG option "allocate with sizeof" is set (made it True by default because it applies only for user specified interfaces since now).

By the way target bug cannot be found because function 'spi_alloc_master' has no model and not tracked as a memory allocating function. But, for example, for false positive in drivers/usb/misc/cytherm.ko (rule linux:usb:dev) new allocation helps to prove driver correctness (new verdict is safe).

Actions #2

Updated by Evgeny Novikov over 8 years ago

  • Status changed from Resolved to Closed
  • Published in build set to 0c2b0af

I merged the given branch to master in 0c2b0af. Since EMG becomes more and more accurate we definitely need CPAchecker that can deal with that (#7454).

Actions #3

Updated by Evgeny Novikov over 8 years ago

  • Status changed from Closed to Open

First look at results showed that sometimes (often) it isn't enough to allocate just memory for callback parameters. For instance, for USB devices pointers to USB interfaces that are just fields of structure usb_device are passed to callbacks. But callbacks quickly get USB devices by using container_of. For the latter memory isn't allocated at all that leads to false alarms as before.

Moreover it seems that environment models don't need to allocate any memory in this case at all! One can try to simply pass to callbacks pointers to corresponding variables of type structure usb_device keeping these callbacks.

The only thing environment models should do in ideal - is to distribute USB interfaces between various modules (devices) but likely we don't need this right now.

I suggest to investigate other false alarms on rule specification linux:usb:dev.

Actions #4

Updated by Ilja Zakharov over 8 years ago

  • Status changed from Open to Resolved

Evgeny, please, close the bug and open the separate one for a particular false alarm. The requested feature is implemented and works as it should do and you are speaking abut a significantly different feature request which is more relevant to specifications improvement.

Actions #5

Updated by Evgeny Novikov about 8 years ago

  • Status changed from Resolved to Closed
  • Published in build changed from 0c2b0af to abe8578

One more step to the specified target was done in branch emg-usb-device that was merged to master in abe8578. In future let's create more concrete issues when some problems with particular interfaces will be thoroughly investigated.

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