[Bug 1908626] Re: Atomic test-and-set instruction does not work on qemu-user

[Thomas Huth]

The QEMU project is currently moving its bug tracking to another system.
For this we need to know which bugs are still valid and which could be
closed already. Thus we are setting the bug state to "Incomplete" now.

If the bug has already been fixed in the latest upstream version of QEMU,
then please close this ticket as "Fix released".

If it is not fixed yet and you think that this bug report here is still
valid, then you have two options:

1) If you already have an account on gitlab.com, please open a new ticket
for this problem in our new tracker here:

    https://gitlab.com/qemu-project/qemu/-/issues

and then close this ticket here on Launchpad (or let it expire auto-
matically after 60 days). Please mention the URL of this bug ticket on
Launchpad in the new ticket on GitLab.

2) If you don't have an account on gitlab.com and don't intend to get
one, but still would like to keep this ticket opened, then please switch
the state back to "New" or "Confirmed" within the next 60 days (other-
wise it will get closed as "Expired"). We will then eventually migrate
the ticket automatically to the new system (but you won't be the reporter
of the bug in the new system and thus you won't get notified on changes
anymore).

Thank you and sorry for the inconvenience.


** Changed in: qemu
       Status: New => Incomplete

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https://bugs.launchpad.net/bugs/1908626

Title:
  Atomic test-and-set instruction does not work on qemu-user

Status in QEMU:
  Incomplete

Bug description:
  I try to compile and run PostgreSQL/Greenplum database inside docker 
container/qemu-aarch64-static:
  ```
   host: CentOS7 x86_64
   container: centos:centos7.9.2009 --platform linux/arm64/v8
   qemu-user-static: https://github.com/multiarch/qemu-user-static/releases/
  ```

  However, GP/PG's spinlock always gets stuck and reports PANIC errors. It 
seems its spinlock
  has something wrong.
  ```
  https://github.com/greenplum-db/gpdb/blob/master/src/include/storage/s_lock.h
  
https://github.com/greenplum-db/gpdb/blob/master/src/backend/storage/lmgr/s_lock.c
  ```

  So I extract its spinlock implementation into one test C source file (see 
attachment file),
  and get reprodcued:

  ```
  $ gcc spinlock_qemu.c
  $ ./a.out 
  C -- slock inited, lock value is: 0
  parent 139642, child 139645
  P -- slock lock before, lock value is: 0
  P -- slock locked, lock value is: 1
  P -- slock unlock after, lock value is: 0
  C -- slock lock before, lock value is: 1
  P -- slock lock before, lock value is: 1
  C -- slock locked, lock value is: 1
  C -- slock unlock after, lock value is: 0
  C -- slock lock before, lock value is: 1
  P -- slock locked, lock value is: 1
  P -- slock unlock after, lock value is: 0
  P -- slock lock before, lock value is: 1
  C -- slock locked, lock value is: 1
  C -- slock unlock after, lock value is: 0
  P -- slock locked, lock value is: 1
  C -- slock lock before, lock value is: 1
  P -- slock unlock after, lock value is: 0
  C -- slock locked, lock value is: 1
  P -- slock lock before, lock value is: 1
  C -- slock unlock after, lock value is: 0
  P -- slock locked, lock value is: 1
  C -- slock lock before, lock value is: 1
  P -- slock unlock after, lock value is: 0
  C -- slock locked, lock value is: 1
  P -- slock lock before, lock value is: 1
  C -- slock unlock after, lock value is: 0
  P -- slock locked, lock value is: 1
  C -- slock lock before, lock value is: 1
  P -- slock unlock after, lock value is: 0
  P -- slock lock before, lock value is: 1
  spin timeout, lock value is 1 (pid 139642)
  spin timeout, lock value is 1 (pid 139645)
  spin timeout, lock value is 1 (pid 139645)
  spin timeout, lock value is 1 (pid 139642)
  spin timeout, lock value is 1 (pid 139645)
  spin timeout, lock value is 1 (pid 139642)
  ...
  ...
  ...
  ```

  NOTE: this code always works on PHYSICAL ARM64 server.

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