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Kernel: Simplify the File memory-mapping API

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Before this change, we had File::mmap() which did all the work of
setting up a VMObject, and then creating a Region in the current
process's address space.

This patch simplifies the interface by removing the region part.
Files now only have to return a suitable VMObject from
vmobject_for_mmap(), and then sys$mmap() itself will take care of
actually mapping it into the address space.

This fixes an issue where we'd try to block on I/O (for inode metadata
lookup) while holding the address space spinlock. It also reduces time
spent holding the address space lock.
This commit is contained in:
Andreas Kling 2022-08-23 18:51:18 +02:00
parent cf16b2c8e6
commit 30861daa93
15 changed files with 49 additions and 58 deletions
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10
Kernel/Graphics/DisplayConnector.cpp
View file

@ -32,19 +32,13 @@ DisplayConnector::DisplayConnector(size_t framebuffer_resource_size, bool enable
{
}
ErrorOr<Memory::Region*> DisplayConnector::mmap(Process&, Memory::AddressSpace& address_space, OpenFileDescription&, Memory::VirtualRange const& range, u64 offset, int prot, bool shared)
ErrorOr<NonnullLockRefPtr<Memory::VMObject>> DisplayConnector::vmobject_for_mmap(Process&, Memory::VirtualRange const&, u64& offset, bool)
{
VERIFY(m_shared_framebuffer_vmobject);
if (offset != 0)
return Error::from_errno(ENOTSUP);
return address_space.allocate_region_with_vmobject(
range,
*m_shared_framebuffer_vmobject,
0,
"Mapped Framebuffer"sv,
prot,
shared);
return *m_shared_framebuffer_vmobject;
}
ErrorOr<size_t> DisplayConnector::read(OpenFileDescription&, u64, UserOrKernelBuffer&, size_t)