From a8377340fd829e70a92fe6060da35f81c0c4a62d Mon Sep 17 00:00:00 2001
From: GabrielPavaloiu <gabrieln.pavaloiu@gmail.com>
Date: Tue, 10 Dec 2024 15:40:57 +0200
Subject: [PATCH 1/2] grant: added remove_pending_upcalls function

Added a method to GrantKernelData that removes all pending upcalls of
the current driver with the given subscriber_num from the process's
upcall queue.
---
 kernel/src/grant.rs | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/kernel/src/grant.rs b/kernel/src/grant.rs
index d8522d9b5c..a101f19cab 100644
--- a/kernel/src/grant.rs
+++ b/kernel/src/grant.rs
@@ -619,6 +619,15 @@ impl<'a> GrantKernelData<'a> {
         )
     }
 
+    /// Remove all scheduled upcalls with the given `subscribe_num` from the
+    /// task queue.
+    pub fn remove_pending_upcalls(&self, subscribe_num: usize) {
+        self.process.remove_pending_upcalls(UpcallId {
+            subscribe_num,
+            driver_num: self.driver_num,
+        });
+    }
+
     /// Returns a lifetime limited reference to the requested
     /// [`ReadOnlyProcessBuffer`].
     ///

From c057fe3438d71537e35728ad476c89c9a928d967 Mon Sep 17 00:00:00 2001
From: GabrielPavaloiu <gabrieln.pavaloiu@gmail.com>
Date: Thu, 12 Dec 2024 13:22:40 +0200
Subject: [PATCH 2/2] {grant, process}: updated remove pending upcalls api

Changed remove_pending_upcalls to return the number of tasks removed.
Added an API to call remove_upcall from GrantKernelData.
---
 kernel/src/grant.rs            | 18 ++++++++++++++++--
 kernel/src/kernel.rs           |  2 +-
 kernel/src/process.rs          |  4 +++-
 kernel/src/process_standard.rs |  9 +++++----
 4 files changed, 25 insertions(+), 8 deletions(-)

diff --git a/kernel/src/grant.rs b/kernel/src/grant.rs
index a101f19cab..ecf2080d8d 100644
--- a/kernel/src/grant.rs
+++ b/kernel/src/grant.rs
@@ -619,13 +619,27 @@ impl<'a> GrantKernelData<'a> {
         )
     }
 
+    /// Search the work queue for the first pending operation with the given
+    /// `subscribe_num` and if one exists remove it from the task queue.
+    ///
+    /// Returns the associated [`Task`] if one was found, otherwise returns
+    /// [`None`].
+    pub fn remove_upcall(&self, subscribe_num: usize) -> Option<crate::process::Task> {
+        self.process.remove_upcall(UpcallId {
+            subscribe_num,
+            driver_num: self.driver_num,
+        })
+    }
+
     /// Remove all scheduled upcalls with the given `subscribe_num` from the
     /// task queue.
-    pub fn remove_pending_upcalls(&self, subscribe_num: usize) {
+    ///
+    /// Returns the number of removed upcalls.
+    pub fn remove_pending_upcalls(&self, subscribe_num: usize) -> usize {
         self.process.remove_pending_upcalls(UpcallId {
             subscribe_num,
             driver_num: self.driver_num,
-        });
+        })
     }
 
     /// Returns a lifetime limited reference to the requested
diff --git a/kernel/src/kernel.rs b/kernel/src/kernel.rs
index b408f0631a..1880d52f01 100644
--- a/kernel/src/kernel.rs
+++ b/kernel/src/kernel.rs
@@ -1017,7 +1017,7 @@ impl Kernel {
                             // that there are no pending upcalls with the same
                             // identifier but with the old function pointer, we
                             // clear them now.
-                            process.remove_pending_upcalls(upcall_id);
+                            let _ =process.remove_pending_upcalls(upcall_id);
                         }
 
                         if config::CONFIG.trace_syscalls {
diff --git a/kernel/src/process.rs b/kernel/src/process.rs
index 3509fa7946..a4b461bff3 100644
--- a/kernel/src/process.rs
+++ b/kernel/src/process.rs
@@ -391,7 +391,9 @@ pub trait Process {
 
     /// Remove all scheduled upcalls with the given `upcall_id` from the task
     /// queue.
-    fn remove_pending_upcalls(&self, upcall_id: UpcallId);
+    ///
+    /// Returns the number of removed upcalls.
+    fn remove_pending_upcalls(&self, upcall_id: UpcallId) -> usize;
 
     /// Returns the current state the process is in.
     fn get_state(&self) -> State;
diff --git a/kernel/src/process_standard.rs b/kernel/src/process_standard.rs
index 5d4dc5592a..87ed46f9e9 100644
--- a/kernel/src/process_standard.rs
+++ b/kernel/src/process_standard.rs
@@ -552,8 +552,8 @@ impl<C: Chip, D: 'static + ProcessStandardDebug> Process for ProcessStandard<'_,
             || self.state.get() == State::Running
     }
 
-    fn remove_pending_upcalls(&self, upcall_id: UpcallId) {
-        self.tasks.map(|tasks| {
+    fn remove_pending_upcalls(&self, upcall_id: UpcallId) -> usize {
+        self.tasks.map_or(0, |tasks| {
             let count_before = tasks.len();
             tasks.retain(|task| match task {
                 // Remove only tasks that are function calls with an id equal
@@ -564,8 +564,8 @@ impl<C: Chip, D: 'static + ProcessStandardDebug> Process for ProcessStandard<'_,
                 },
                 _ => true,
             });
+            let count_after = tasks.len();
             if config::CONFIG.trace_syscalls {
-                let count_after = tasks.len();
                 debug!(
                     "[{:?}] remove_pending_upcalls[{:#x}:{}] = {} upcall(s) removed",
                     self.processid(),
@@ -574,7 +574,8 @@ impl<C: Chip, D: 'static + ProcessStandardDebug> Process for ProcessStandard<'_,
                     count_before - count_after,
                 );
             }
-        });
+            count_after - count_before
+        })
     }
 
     fn is_running(&self) -> bool {