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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?8a72KfsVZkOGX+FICVEm34rsRVB1emUcR3uom1zDzvhOWZ5iqrnU2bZ1W2GE?= =?us-ascii?Q?4G8JDuQUFRwVaYziCobcKAoGgxyoOBSwCnAlUrN75Y1e0tZry4seoaCcIz6y?= =?us-ascii?Q?1U3h7sPkPNie4ML4kygfRjRwrXXWGLRUQXOZbaRGKfZfr7EywEhfOE7PyUcL?= =?us-ascii?Q?x1K5GY+lJ5jojt7zhje5M7buZHb0byJyhYOCa2L3WDJnJs/b+7YqNbNPCKli?= =?us-ascii?Q?GGtY4ysP3kjl5GG8FjftyxsWdnWFbFNuOH54noj56SsyAAaL1ajeqT098nrz?= =?us-ascii?Q?ITydVtWzGD5QpdJ+3ZTzAOIp1BKnjZXqdXKiKyk9T6H0dOE7j9f8N66/WBzH?= =?us-ascii?Q?RhT37LZIQQfWTctAob0yl1s2t/55abuCzSYCM05VpEYh5Mimqezo+j9bInOg?= =?us-ascii?Q?IrMLW1SFksW8ezMJezi1KzZw0mk4WVUOi0++0zeg7xKzLM72Sbf4Q60lCdwu?= =?us-ascii?Q?c0CYXZCZ610KTrmI28TnQqWNBoz/Bn/G04YxzYOyM39qtBNXyXTBQysxKXiY?= =?us-ascii?Q?ted4xu2CsD/AhfetG4fJdaX1Pe5XB8IKqN1jmiL5N0YE8IyWOZgNN8kihs4E?= =?us-ascii?Q?nf6jq+8Tk2rZ5iQQCjuaH+3xQT5FuTNauOuhKdQaOZE1qMVd12FYspLALh/v?= =?us-ascii?Q?jIDXM1GLuV2YSm5cHO8hDWI2JQHbiH7ZNa+uodU5YHTDvMMYlPP954dvm8K2?= =?us-ascii?Q?TRfNZweflxYBR/yMuDhtl5B/++YmL8hd9ncnUnQpE5xCJflbfE7v8wJFpeIC?= =?us-ascii?Q?0Bnlq2Q4Tg8LY4RLZbuS24h+xcufW7RJvYIwrpARgLOze3n8Gmew01DxMZif?= =?us-ascii?Q?ER72/BSRsYDGc47yGcgk+mMVezh/u10PevmSqvvQhdsw5nQIB7Na3qwPwolo?= =?us-ascii?Q?kBNz901S5kfDgQEnnOXpaLbE8Y8qai+MhZlYLafT3/epCGAhh+mT8dX90yYx?= =?us-ascii?Q?M6oq2FarTrcQ4qp+lpryB00Yt52vjlXOa3v4dSVXJem17EP7K+F48Znwth25?= =?us-ascii?Q?X16XPOnnLjKYiigzep8WbjtO3PY63Sn4xj53VYnCdL9m28DkaM/0fpBjAd+I?= =?us-ascii?Q?Xb5QPKjPweffZMYUnNIruPRA5WOmymkPdbdzg5QljHLdCuzDBLBQOSABRy3U?= =?us-ascii?Q?yzvNuP21bnXvjZxZsCRLaBuwWlzZr03xvG3RgjfanY60v1+goLO+lE4xIh9P?= =?us-ascii?Q?Y1n1pxuN/uBSumDEOvWQV+Nw504dAZ0RiDrcXLx18JwhGG33gYPsmHOYgba1?= =?us-ascii?Q?kfszzmjx3jmjaK5mT7UzNPBSpzi2uctQ7iG1wkIQhXDnn2xVqowlqlCFlead?= =?us-ascii?Q?Ux3mXNzJc/XpQuoW8S7/4KcTxuM0wnKL9kBS+b3DlLeIjgWt19uq8bGFj7nz?= =?us-ascii?Q?GK+gTTmBmjdyavrq5rqvIUPCFlQQVk8FUO5rSD0r/WHmE8EUbrb7pll30Cv2?= =?us-ascii?Q?o7lskvUJTa3bcpyL8gP/8Wl1M6VxhQ7RiZNRSBbAOjHwfBIIRbHHslPp+FTD?= =?us-ascii?Q?/4ugaAt54aV4Kfz6PHsGe0ApTZgeINofqO245djKihv1moFEk22SyZTWIIEF?= =?us-ascii?Q?HK7RJg0HsCxLldpjaMS8LZr9JQKQRNjyT4OyNWOLHIUAVkqcCL3CVbbsOkau?= =?us-ascii?Q?tQ=3D=3D?= X-OriginatorOrg: garyguo.net X-MS-Exchange-CrossTenant-Network-Message-Id: 87409d62-656e-4e8d-f833-08dd2dbbb38a X-MS-Exchange-CrossTenant-AuthSource: LO2P265MB5183.GBRP265.PROD.OUTLOOK.COM X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 05 Jan 2025 19:03:55.3611 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: bbc898ad-b10f-4e10-8552-d9377b823d45 X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: +p5C7Yvs84IL2Q6d9xLgq+DmR1invYGfJ57Q6fD4ZOACp2AoEm3KZ5C3EQhU7S5gvwJqP/BUCQmYV2BxaNIbKA== X-MS-Exchange-Transport-CrossTenantHeadersStamped: LO6P265MB7384 On Fri, 3 Jan 2025 17:58:37 +0100 Danilo Krummrich wrote: > On Fri, Jan 03, 2025 at 05:44:31PM +0100, Danilo Krummrich wrote: > > So far `DevresInner` is kept alive, even if `Devres` is dropped until > > the devres callback is executed to avoid a WARN() when the action has > > been released already. > > > > With the introduction of devm_remove_action_nowarn() we can remove the > > action in `Devres::drop`, handle the case where the action has been > > released already and hence also free `DevresInner`. > > > > Signed-off-by: Danilo Krummrich Hi Danilo, Thanks for sending this. Feel free to add Reviewed-by: Gary Guo for both patches with the `revoke_nosync` removed as you mentioned. Best, Gary > > --- > > rust/kernel/devres.rs | 56 +++++++++++++++++++++++++++++++++---------- > > 1 file changed, 44 insertions(+), 12 deletions(-) > > > > diff --git a/rust/kernel/devres.rs b/rust/kernel/devres.rs > > index 9c9dd39584eb..7d3daac92109 100644 > > --- a/rust/kernel/devres.rs > > +++ b/rust/kernel/devres.rs > > @@ -10,15 +10,19 @@ > > bindings, > > device::Device, > > error::{Error, Result}, > > + ffi::c_void, > > prelude::*, > > revocable::Revocable, > > sync::Arc, > > + types::ARef, > > }; > > > > use core::ops::Deref; > > > > #[pin_data] > > struct DevresInner { > > + dev: ARef, > > + callback: unsafe extern "C" fn(*mut c_void), > > #[pin] > > data: Revocable, > > } > > @@ -98,6 +102,8 @@ impl DevresInner { > > fn new(dev: &Device, data: T, flags: Flags) -> Result>> { > > let inner = Arc::pin_init( > > pin_init!( DevresInner { > > + dev: dev.into(), > > + callback: Self::devres_callback, > > data <- Revocable::new(data), > > }), > > flags, > > @@ -109,9 +115,8 @@ fn new(dev: &Device, data: T, flags: Flags) -> Result>> { > > > > // SAFETY: `devm_add_action` guarantees to call `Self::devres_callback` once `dev` is > > // detached. > > - let ret = unsafe { > > - bindings::devm_add_action(dev.as_raw(), Some(Self::devres_callback), data as _) > > - }; > > + let ret = > > + unsafe { bindings::devm_add_action(dev.as_raw(), Some(inner.callback), data as _) }; > > > > if ret != 0 { > > // SAFETY: We just created another reference to `inner` in order to pass it to > > @@ -124,6 +129,41 @@ fn new(dev: &Device, data: T, flags: Flags) -> Result>> { > > Ok(inner) > > } > > > > + fn as_ptr(&self) -> *const Self { > > + self as _ > > + } > > + > > + fn remove_action(&self) { > > + // SAFETY: > > + // - `self.inner.dev` is a valid `Device`, > > + // - the `action` and `data` pointers are the exact same ones as given to devm_add_action() > > + // previously, > > + // - `self` is always valid, even if the action has been released already. > > + let ret = unsafe { > > + bindings::devm_remove_action_nowarn( > > + self.dev.as_raw(), > > + Some(self.callback), > > + self.as_ptr() as _, > > + ) > > + }; > > + > > + if ret != 0 { > > + // The devres action has been released already - nothing to do. > > + return; > > + } > > + > > + // SAFETY: We leaked an `Arc` reference to devm_add_action() in `DevresInner::new`; if > > + // devm_remove_action_nowarn() was successful we can (and have to) claim back ownership of > > + // this reference. > > + let _ = unsafe { Arc::from_raw(self.as_ptr()) }; > > + > > + // Revoke the data, such that it gets dropped and the actual resource is freed. > > + // > > + // SAFETY: When `drop` runs, it's guaranteed that nobody is accessing the revocable data > > + // anymore, hence it is safe not to wait for the grace period to finish. > > + unsafe { self.data.revoke_nosync() }; > > With this patch, this shouldn't be needed any longer -- forgot to remove it. > > > + } > > + > > #[allow(clippy::missing_safety_doc)] > > unsafe extern "C" fn devres_callback(ptr: *mut kernel::ffi::c_void) { > > let ptr = ptr as *mut DevresInner; > > @@ -165,14 +205,6 @@ fn deref(&self) -> &Self::Target { > > > > impl Drop for Devres { > > fn drop(&mut self) { > > - // Revoke the data, such that it gets dropped already and the actual resource is freed. > > - // > > - // `DevresInner` has to stay alive until the devres callback has been called. This is > > - // necessary since we don't know when `Devres` is dropped and calling > > - // `devm_remove_action()` instead could race with `devres_release_all()`. > > - // > > - // SAFETY: When `drop` runs, it's guaranteed that nobody is accessing the revocable data > > - // anymore, hence it is safe not to wait for the grace period to finish. > > - unsafe { self.revoke_nosync() }; > > + self.0.remove_action(); > > } > > } > > -- > > 2.47.1 > >