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also clean up eventfd code in the same vein

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This commit is contained in:
Ralf Jung 2024-12-27 12:32:04 +01:00
parent 75209df948
commit 6383513249
1 changed files with 25 additions and 30 deletions
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55
src/tools/miri/src/shims/unix/linux_like/eventfd.rs
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@ -62,11 +62,10 @@ impl FileDescription for Event {
return ecx.set_last_error_and_return(ErrorKind::InvalidInput, dest);
}
// eventfd read at the size of u64.
// Turn the pointer into a place at the right type.
let buf_place = ecx.ptr_to_mplace_unaligned(ptr, ty);
let weak_eventfd = self_ref.downgrade();
eventfd_read(buf_place, dest, weak_eventfd, ecx)
eventfd_read(buf_place, dest, self_ref, ecx)
}
/// A write call adds the 8-byte integer value supplied in
@ -97,18 +96,10 @@ impl FileDescription for Event {
return ecx.set_last_error_and_return(ErrorKind::InvalidInput, dest);
}
// Read the user-supplied value from the pointer.
// Turn the pointer into a place at the right type.
let buf_place = ecx.ptr_to_mplace_unaligned(ptr, ty);
let num = ecx.read_scalar(&buf_place)?.to_u64()?;
// u64::MAX as input is invalid because the maximum value of counter is u64::MAX - 1.
if num == u64::MAX {
return ecx.set_last_error_and_return(ErrorKind::InvalidInput, dest);
}
// If the addition does not let the counter to exceed the maximum value, update the counter.
// Else, block.
let weak_eventfd = self_ref.downgrade();
eventfd_write(num, buf_place, dest, weak_eventfd, ecx)
eventfd_write(buf_place, dest, self_ref, ecx)
}
fn as_unix(&self) -> &dyn UnixFileDescription {
@ -193,20 +184,22 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
/// Block thread if the value addition will exceed u64::MAX -1,
/// else just add the user-supplied value to current counter.
fn eventfd_write<'tcx>(
num: u64,
buf_place: MPlaceTy<'tcx>,
dest: &MPlaceTy<'tcx>,
weak_eventfd: WeakFileDescriptionRef,
eventfd_ref: &FileDescriptionRef,
ecx: &mut MiriInterpCx<'tcx>,
) -> InterpResult<'tcx> {
let Some(eventfd_ref) = weak_eventfd.upgrade() else {
throw_unsup_format!("eventfd FD got closed while blocking.")
};
// Since we pass the weak file description ref, it is guaranteed to be
// an eventfd file description.
let eventfd = eventfd_ref.downcast::<Event>().unwrap();
// Figure out which value we should add.
let num = ecx.read_scalar(&buf_place)?.to_u64()?;
// u64::MAX as input is invalid because the maximum value of counter is u64::MAX - 1.
if num == u64::MAX {
return ecx.set_last_error_and_return(ErrorKind::InvalidInput, dest);
}
match eventfd.counter.get().checked_add(num) {
Some(new_count @ 0..=MAX_COUNTER) => {
// Future `read` calls will synchronize with this write, so update the FD clock.
@ -219,7 +212,7 @@ fn eventfd_write<'tcx>(
// The state changed; we check and update the status of all supported event
// types for current file description.
ecx.check_and_update_readiness(&eventfd_ref)?;
ecx.check_and_update_readiness(eventfd_ref)?;
// Unblock *all* threads previously blocked on `read`.
// We need to take out the blocked thread ids and unblock them together,
@ -244,6 +237,7 @@ fn eventfd_write<'tcx>(
eventfd.blocked_write_tid.borrow_mut().push(ecx.active_thread());
let weak_eventfd = eventfd_ref.downgrade();
ecx.block_thread(
BlockReason::Eventfd,
None,
@ -255,8 +249,10 @@ fn eventfd_write<'tcx>(
weak_eventfd: WeakFileDescriptionRef,
}
@unblock = |this| {
// When we get unblocked, try again.
eventfd_write(num, buf_place, &dest, weak_eventfd, this)
// When we get unblocked, try again. We know the ref is still valid,
// otherwise there couldn't be a `write` that unblocks us.
let eventfd_ref = weak_eventfd.upgrade().unwrap();
eventfd_write(buf_place, &dest, &eventfd_ref, this)
}
),
);
@ -270,13 +266,9 @@ fn eventfd_write<'tcx>(
fn eventfd_read<'tcx>(
buf_place: MPlaceTy<'tcx>,
dest: &MPlaceTy<'tcx>,
weak_eventfd: WeakFileDescriptionRef,
eventfd_ref: &FileDescriptionRef,
ecx: &mut MiriInterpCx<'tcx>,
) -> InterpResult<'tcx> {
let Some(eventfd_ref) = weak_eventfd.upgrade() else {
throw_unsup_format!("eventfd FD got closed while blocking.")
};
// Since we pass the weak file description ref to the callback function, it is guaranteed to be
// an eventfd file description.
let eventfd = eventfd_ref.downcast::<Event>().unwrap();
@ -293,6 +285,7 @@ fn eventfd_read<'tcx>(
eventfd.blocked_read_tid.borrow_mut().push(ecx.active_thread());
let weak_eventfd = eventfd_ref.downgrade();
ecx.block_thread(
BlockReason::Eventfd,
None,
@ -303,8 +296,10 @@ fn eventfd_read<'tcx>(
weak_eventfd: WeakFileDescriptionRef,
}
@unblock = |this| {
// When we get unblocked, try again.
eventfd_read(buf_place, &dest, weak_eventfd, this)
// When we get unblocked, try again. We know the ref is still valid,
// otherwise there couldn't be a `write` that unblocks us.
let eventfd_ref = weak_eventfd.upgrade().unwrap();
eventfd_read(buf_place, &dest, &eventfd_ref, this)
}
),
);
@ -317,7 +312,7 @@ fn eventfd_read<'tcx>(
// The state changed; we check and update the status of all supported event
// types for current file description.
ecx.check_and_update_readiness(&eventfd_ref)?;
ecx.check_and_update_readiness(eventfd_ref)?;
// Unblock *all* threads previously blocked on `write`.
// We need to take out the blocked thread ids and unblock them together,