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gpio: guard libgpiod::Chip with Mutex

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The Chip is not `Sync` (as wrongly claimed by the `Sync` marker on
`PhysDevice`). So if we want to share the `PhysDevice` across threads,
we will need to guard it by a `Mutex`.

These calls do not block for very long. So this should not cause any new
deadlock conditions.

Issue: #442
Signed-off-by: Erik Schilling <erik.schilling@linaro.org>
This commit is contained in:
Erik Schilling 2023-09-28 12:03:21 +02:00 committed by Viresh Kumar
parent bde810043d
commit 340a3f82dd
1 changed files with 17 additions and 18 deletions
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35
crates/vhost-device-gpio/src/gpio.rs
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@ -91,7 +91,7 @@ pub(crate) struct PhysLineState {
}
pub(crate) struct PhysDevice {
chip: chip::Chip,
chip: Mutex<chip::Chip>,
ngpio: u16,
state: Vec<RwLock<PhysLineState>>,
}
@ -121,7 +121,11 @@ impl GpioDevice for PhysDevice {
})
});
Ok(PhysDevice { chip, ngpio, state })
Ok(PhysDevice {
chip: Mutex::new(chip),
ngpio,
state,
})
}
fn num_gpios(&self) -> Result<u16> {
@ -131,6 +135,8 @@ impl GpioDevice for PhysDevice {
fn gpio_name(&self, gpio: u16) -> Result<String> {
let line_info = self
.chip
.lock()
.unwrap()
.line_info(gpio.into())
.map_err(Error::GpiodFailed)?;
@ -140,6 +146,8 @@ impl GpioDevice for PhysDevice {
fn direction(&self, gpio: u16) -> Result<u8> {
let line_info = self
.chip
.lock()
.unwrap()
.line_info(gpio.into())
.map_err(Error::GpiodFailed)?;
@ -195,22 +203,13 @@ impl GpioDevice for PhysDevice {
.set_consumer("vhu-gpio")
.map_err(Error::GpiodFailed)?;
// This is causing a warning since libgpiod's request_config is
// not `Send`.
// We, however, unsafely claim that it is by marking PhysDevice as
// `Send`. This is wrong, but until we figure out what to do, we
// just silence the clippy warning here.
//
// https://github.com/rust-vmm/vhost-device/issues/442 tracks
// finding a solution to this.
#[allow(clippy::arc_with_non_send_sync)]
{
state.request = Some(Arc::new(Mutex::new(
self.chip
.request_lines(Some(&rconfig), &lconfig)
.map_err(Error::GpiodFailed)?,
)));
}
state.request = Some(
self.chip
.lock()
.unwrap()
.request_lines(Some(&rconfig), &lconfig)
.map_err(Error::GpiodFailed)?,
);
}
Ok(())