[GitHub] [incubator-nuttx] raiden00pl commented on issue #6012: Low priority tasks interrupt high priority threads

[GitBox <gi...@apache.org>]

raiden00pl commented on issue #6012:
URL: https://github.com/apache/incubator-nuttx/issues/6012#issuecomment-1094096841

   I think I know what's going on.
   
   I set breakpoint in `arm_svcall,` which is triggered when pthread is interrupted.
   What I found is that pthread is waiting for semaphore in `fs/inode/fs_files.c` and this switch execution to low priority main.
   
   When I removed `nxsem_wait_uninterruptible` from `_files_semtake` pthread is never interrupted.
   
   It goes more or less like this:
     1. low priority main wakes up just before FOC interrupt
     2. main gets `fs/inode/fs_files.c` semaphore (`fs_getfilep` -> `_files_semtake`)
     3. FOC interrupt occurs and wakes up FOC pthread
     4. pthread tries to get `fs/inodefs_files.c` semaphtore
     5. pthread waits for semaphore
     6. context switch to main
   


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