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Kernel/NVMe: Use an Atomic for command id instead of sq index

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Using sq_tail as cid makes an inherent assumption that we send only
one IO at a time. Use an atomic variable instead for command id of a
submission queue entry.

As sq_tail is not used as cid anymore, remove m_prev_sq_tail which used
to hold the last used sq_tail value.
This commit is contained in:
Pankaj Raghav 2023-03-29 10:25:04 +02:00 • committed by Jelle Raaijmakers
parent e219662ce0
commit 3fe7bda021
2 changed files with 18 additions and 7 deletions
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15
Kernel/Storage/NVMe/NVMeQueue.h
View file

@ -44,6 +44,19 @@ protected:
}
NVMeQueue(NonnullOwnPtr<Memory::Region> rw_dma_region, Memory::PhysicalPage const& rw_dma_page, u16 qid, u32 q_depth, OwnPtr<Memory::Region> cq_dma_region, Vector<NonnullRefPtr<Memory::PhysicalPage>> cq_dma_page, OwnPtr<Memory::Region> sq_dma_region, Vector<NonnullRefPtr<Memory::PhysicalPage>> sq_dma_page, Memory::TypedMapping<DoorbellRegister volatile> db_regs);
[[nodiscard]] u32 get_request_cid()
{
u32 expected_tag = m_tag.load(AK::memory_order_acquire);
for (;;) {
u32 cid = expected_tag + 1;
if (cid == m_qdepth)
cid = 0;
if (m_tag.compare_exchange_strong(expected_tag, cid, AK::memory_order_acquire))
return cid;
}
}
private:
bool cqe_available();
void update_cqe_head();
@ -63,10 +76,10 @@ private:
u16 m_qid {};
u8 m_cq_valid_phase { 1 };
u16 m_sq_tail {};
u16 m_prev_sq_tail {};
u16 m_cq_head {};
bool m_admin_queue { false };
u32 m_qdepth {};
Atomic<u32> m_tag { 0 }; // used for the cid in a submission queue entry
Spinlock<LockRank::Interrupts> m_sq_lock {};
OwnPtr<Memory::Region> m_cq_dma_region;
Vector<NonnullRefPtr<Memory::PhysicalPage>> m_cq_dma_page;