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Kernel: Thread::wait_on() must always leave interrupts enabled on exit

The short-circuit path added for waiting on a queue that already had a
pending wake was able to return with interrupts disabled, which breaks
the API contract of wait_on() always returning with IF=1.

Fix this by adding a way to override the restored IF in ScopedCritical.
This commit is contained in:
Andreas Kling 2020-07-06 11:31:21 +02:00
parent 3e0020e67d
commit 163c9d5f8f
2 changed files with 13 additions and 0 deletions

View file

@ -837,6 +837,14 @@ public:
return *this; return *this;
} }
void set_interrupt_flag_on_destruction(bool flag)
{
if (flag)
m_prev_flags |= 0x200;
else
m_prev_flags &= ~0x200;
}
private: private:
u32 m_prev_flags { 0 }; u32 m_prev_flags { 0 };
bool m_valid { false }; bool m_valid { false };

View file

@ -876,6 +876,11 @@ Thread::BlockResult Thread::wait_on(WaitQueue& queue, const char* reason, timeva
// The WaitQueue was already requested to wake someone when // The WaitQueue was already requested to wake someone when
// nobody was waiting. So return right away as we shouldn't // nobody was waiting. So return right away as we shouldn't
// be waiting // be waiting
// The API contract guarantees we return with interrupts enabled,
// regardless of how we got called
critical.set_interrupt_flag_on_destruction(true);
return BlockResult::NotBlocked; return BlockResult::NotBlocked;
} }