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Eliminate deadlock in capture_inner

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This commit is contained in:
Jeremy Soller
2022-08-27 07:48:47 -06:00
parent 6f6648c4d2
commit 1fadde3ee8
1 changed files with 20 additions and 8 deletions
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28
src/scheme/user.rs
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@@ -150,21 +150,33 @@ impl UserInner {
return Ok(VirtualAddress::new(DANGLING));
}
let dst_addr_space = Arc::clone(context_weak.upgrade().ok_or(Error::new(ESRCH))?.read().addr_space()?);
let mut dst_addr_space = dst_addr_space.write();
let src_page = Page::containing_address(VirtualAddress::new(round_down_pages(address)));
let offset = address - src_page.start_address().data();
let page_count = round_up_pages(offset + size) / PAGE_SIZE;
let requested_dst_page = (dst_address != 0).then_some(Page::containing_address(VirtualAddress::new(round_down_pages(dst_address))));
let current_addrspace = AddrSpace::current()?;
let mut current_addrspace = current_addrspace.write();
let dst_space_lock = Arc::clone(context_weak.upgrade().ok_or(Error::new(ESRCH))?.read().addr_space()?);
let cur_space_lock = AddrSpace::current()?;
//TODO: Use syscall_head and syscall_tail to avoid leaking data
let dst_page = dst_addr_space.mmap(requested_dst_page, page_count, flags, |dst_page, page_flags, mapper, flusher| {
Ok(Grant::borrow(src_page, dst_page, page_count, page_flags, desc_opt, &mut current_addrspace.table.utable, mapper, flusher)?)
})?;
let dst_page = if Arc::ptr_eq(
&dst_space_lock,
&cur_space_lock,
) {
let mut dst_space = dst_space_lock.write();
dst_space.mmap(requested_dst_page, page_count, flags, |dst_page, page_flags, mapper, flusher| {
//TODO: remove hack to use same mapper for borrow
let src_mapper = unsafe { &mut *(mapper as *mut _) };
let dst_mapper = unsafe { &mut *(mapper as *mut _) };
Ok(Grant::borrow(src_page, dst_page, page_count, page_flags, desc_opt, src_mapper, dst_mapper, flusher)?)
})?
} else {
let mut dst_space = dst_space_lock.write();
dst_space.mmap(requested_dst_page, page_count, flags, move |dst_page, page_flags, mapper, flusher| {
let mut cur_space = cur_space_lock.write();
Ok(Grant::borrow(src_page, dst_page, page_count, page_flags, desc_opt, &mut cur_space.table.utable, mapper, flusher)?)
})?
};
Ok(dst_page.start_address().add(offset))
}