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cpu/native: fix race in thread_yield_higher() [backport 2019.01] #10921

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merged 2 commits into from
Feb 1, 2019
Merged

cpu/native: fix race in thread_yield_higher() [backport 2019.01] #10921

merged 2 commits into from
Feb 1, 2019

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miri64
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@miri64 miri64 commented Feb 1, 2019

Backport of #10891

Contribution description

Error case:
1. thread_yield_higher() stores the thread's ucontext
2. creates an "isr ucontext" for isr_thread_yield, switches to it

Case 1: no signals are pending, continues in isr_thread_yield()
3a. sched_run is called
4a. return to sched_active_thread ucontext

Case 2: signals pending (the crashing scenario), continues in native_irq_handler()
3b. handles signals
4b. if sched_context_switch_request is set, call sched_run
5b. return to sched_active_thread ucontext

4b misses the call to sched_run(), leading to a possible return into a
non-ready thread.

Fixes #10881.

Testing procedure

See #10881 and #10908

Issues/PRs references

Fixes #10881.
Fixes #6123.

@kaspar030 @miri64
cpu/native: fix race condition in thread_yield_higher()
84a5c4f 
Error case:
1. thread_yield_higher() stores the thread's ucontext
2. creates an "isr ucontext" for isr_thread_yield, switches to it

Case 1: no signals are pending, continues in isr_thread_yield()
3a. sched_run is called
4a. return to sched_active_thread ucontext

Case 2: signals pending (the crashing scenario), continues in native_irq_handler()
3b. handles signals
4b. if sched_context_switch_request is set, call sched_run
5b. return to sched_active_thread ucontext

4b misses the call to sched_run(), leading to a possible return into a
non-ready thread.

(cherry picked from commit 62bb4cc)
@kaspar030 @miri64
core/msg: add assert for problem identified in RIOT-OS#10881
b3ede8d 
(cherry picked from commit 82b2362)
@miri64 miri64 added CI: ready for build If set, CI server will compile all applications for all available boards for the labeled PR Community: Hack'n'ACK candidate This PR is a candidate for review and discussion during one of RIOT's monthly Hack'n'ACK parties Impact: major The PR changes a significant part of the code base. It should be reviewed carefully Platform: native Platform: This PR/issue effects the native platform Process: release backport Integration Process: The PR is a release backport of a change previously provided to master Type: bug The issue reports a bug / The PR fixes a bug (including spelling errors) labels Feb 1, 2019
@miri64 miri64 requested a review from kaspar030 February 1, 2019 15:23
@miri64 miri64 mentioned this pull request Feb 1, 2019
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kaspar030
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ACK.

@miri64
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miri64 commented Feb 1, 2019

I don't believe this is a sensible ACK 😆

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I don't believe this is a sensible ACK laughing

Not all ACKs are created equal? 😉

Seriously, the code it touches hasn't been changed in a long while. The change is as valid as in master. If it compiles and finishes the CI-tests, what could possibly go wrong?

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miri64 commented Feb 1, 2019

what could possibly go wrong?

Famous last words ;-P

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miri64 commented Feb 1, 2019

But on a more somber note: I prefer if a person that is not us two would have a look before we merge this into the stable branch.

emmanuelsearch
emmanuelsearch approved these changes Feb 1, 2019
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clean backport ;)

@emmanuelsearch emmanuelsearch merged commit 1a4d083 into RIOT-OS:2019.01-branch Feb 1, 2019
@miri64 miri64 deleted the backport/2019.01/fix_native_thread_yield_higher branch February 1, 2019 16:08
@aabadie aabadie added this to the Release 2019.01 milestone Feb 1, 2019
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@aabadie aabadie Awaiting requested review from aabadie

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CI: ready for build If set, CI server will compile all applications for all available boards for the labeled PR Community: Hack'n'ACK candidate This PR is a candidate for review and discussion during one of RIOT's monthly Hack'n'ACK parties Impact: major The PR changes a significant part of the code base. It should be reviewed carefully Platform: native Platform: This PR/issue effects the native platform Process: release backport Integration Process: The PR is a release backport of a change previously provided to master Type: bug The issue reports a bug / The PR fixes a bug (including spelling errors)
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