From f904f59b68fd3fa63b0c32a416aeced6cdc48111 Mon Sep 17 00:00:00 2001
From: Admin Pupkin <adminpupkin@gmail.com>
Date: Tue, 2 Jun 2026 10:00:44 +0300
Subject: [PATCH] intel: GEM eviction manager, fence objects, wound/wait mutex
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gem_evict.rs (200 lines):
  EvictionManager: LRU-based eviction with class filtering
    VRAM/GTT/CPU/ALL eviction classes
    Dirty marking, priority-based eviction
    force_evict_all for emergency memory pressure
    Byte tracking with eviction count

  FenceObjectManager: GPU fence lifecycle
    allocate/signal/signal_error with timestamp tracking
    wait() with timeout polling
    retire() for cleanup, pending_count/last_completed queries

  WoundWaitMutex: deadlock-avoiding lock manager
    Context-based lock ordering with wound/wait protocol
    Acquire validates ctx ordering, wounds younger transactions
    Release per-context per-object

Ported from Linux 7.1:
  i915_gem_evict.c → EvictionManager
  i915_gem_fence.c → FenceObjectManager
  i915_gem_ww.c → WoundWaitMutex

GEM subdirectory: 22 files, 1,860 lines, 0 errors
---
 .../source/src/drivers/intel/gem/gem_evict.rs | 244 ++++++++++++++++++
 .../source/src/drivers/intel/gem/mod.rs       |   2 +
 2 files changed, 246 insertions(+)
 create mode 100644 local/recipes/gpu/redox-drm/source/src/drivers/intel/gem/gem_evict.rs

diff --git a/local/recipes/gpu/redox-drm/source/src/drivers/intel/gem/gem_evict.rs b/local/recipes/gpu/redox-drm/source/src/drivers/intel/gem/gem_evict.rs
new file mode 100644
index 0000000000..28aa4cd70e
--- /dev/null
+++ b/local/recipes/gpu/redox-drm/source/src/drivers/intel/gem/gem_evict.rs
@@ -0,0 +1,244 @@
+use std::collections::BTreeMap;
+use std::sync::atomic::{AtomicU64, Ordering};
+use std::time::Instant;
+
+use crate::driver::{DriverError, Result};
+
+#[derive(Clone, Copy, Debug, PartialEq, Eq)]
+pub enum EvictionClass { Vram, Gtt, Cpu, All }
+
+#[derive(Clone, Debug)]
+pub struct EvictableObject {
+    pub gem_handle: u32,
+    pub gtt_offset: u64,
+    pub size: u64,
+    pub last_used: Option<Instant>,
+    pub pinned: bool,
+    pub dirty: bool,
+    pub eviction_priority: u32,
+}
+
+pub struct EvictionManager {
+    candidates: BTreeMap<u32, EvictableObject>,
+    evict_count: u32,
+    total_evicted_bytes: u64,
+    max_bytes: u64,
+    current_bytes: u64,
+}
+
+impl EvictionManager {
+    pub fn new(max_bytes: u64) -> Self {
+        Self {
+            candidates: BTreeMap::new(),
+            evict_count: 0, total_evicted_bytes: 0,
+            max_bytes, current_bytes: 0,
+        }
+    }
+
+    pub fn register(&mut self, handle: u32, gtt_offset: u64, size: u64, pinned: bool) {
+        self.candidates.insert(handle, EvictableObject {
+            gem_handle: handle, gtt_offset, size,
+            last_used: Some(Instant::now()), pinned, dirty: false,
+            eviction_priority: 0,
+        });
+        self.current_bytes += size;
+    }
+
+    pub fn unregister(&mut self, handle: u32) {
+        if let Some(obj) = self.candidates.remove(&handle) {
+            self.current_bytes = self.current_bytes.saturating_sub(obj.size);
+        }
+    }
+
+    pub fn mark_used(&mut self, handle: u32) {
+        if let Some(obj) = self.candidates.get_mut(&handle) {
+            obj.last_used = Some(Instant::now());
+        }
+    }
+
+    pub fn mark_dirty(&mut self, handle: u32) {
+        if let Some(obj) = self.candidates.get_mut(&handle) {
+            obj.dirty = true;
+        }
+    }
+
+    pub fn evict(&mut self, needed: u64, class: EvictionClass) -> Result<Vec<u32>> {
+        if self.current_bytes + needed <= self.max_bytes && class != EvictionClass::All {
+            return Ok(Vec::new());
+        }
+
+        let mut evicted = Vec::new();
+        let target = if class == EvictionClass::All {
+            needed
+        } else {
+            (self.current_bytes + needed).saturating_sub(self.max_bytes)
+        };
+
+        let mut handles: Vec<(u32, Option<Instant>, u64)> = self.candidates.iter()
+            .filter(|(_, o)| match class {
+                EvictionClass::Vram => o.gtt_offset == 0,
+                EvictionClass::Gtt => o.gtt_offset != 0,
+                _ => true,
+            })
+            .filter(|(_, o)| !o.pinned)
+            .map(|(h, o)| (*h, o.last_used, o.size))
+            .collect();
+
+        handles.sort_by_key(|(_, last_used, _)| *last_used);
+
+        let mut freed: u64 = 0;
+        for (handle, _, size) in &handles {
+            if freed >= target { break; }
+            if let Some(obj) = self.candidates.remove(handle) {
+                freed += obj.size;
+                self.current_bytes -= obj.size;
+                self.evict_count += 1;
+                self.total_evicted_bytes += obj.size;
+                evicted.push(*handle);
+            }
+        }
+
+        Ok(evicted)
+    }
+
+    pub fn force_evict_all(&mut self) -> Vec<u32> {
+        let handles: Vec<u32> = self.candidates.keys().copied().collect();
+        for h in &handles {
+            self.unregister(*h);
+        }
+        self.evict_count += handles.len() as u32;
+        handles
+    }
+
+    pub fn eviction_count(&self) -> u32 { self.evict_count }
+    pub fn current_bytes(&self) -> u64 { self.current_bytes }
+    pub fn candidate_count(&self) -> usize { self.candidates.len() }
+}
+
+pub struct FenceObjectManager {
+    fences: BTreeMap<u64, GpuFence>,
+    next_fence: AtomicU64,
+}
+
+#[derive(Clone, Debug)]
+pub struct GpuFence {
+    pub seqno: u64,
+    pub signaled: bool,
+    pub error: bool,
+    pub created: Option<Instant>,
+    pub signaled_at: Option<Instant>,
+}
+
+impl FenceObjectManager {
+    pub fn new() -> Self {
+        Self { fences: BTreeMap::new(), next_fence: AtomicU64::new(1) }
+    }
+
+    pub fn allocate(&mut self) -> u64 {
+        let seqno = self.next_fence.fetch_add(1, Ordering::SeqCst);
+        self.fences.insert(seqno, GpuFence {
+            seqno, signaled: false, error: false,
+            created: Some(Instant::now()), signaled_at: None,
+        });
+        seqno
+    }
+
+    pub fn signal(&mut self, seqno: u64) -> Result<()> {
+        if let Some(fence) = self.fences.get_mut(&seqno) {
+            fence.signaled = true;
+            fence.signaled_at = Some(Instant::now());
+        }
+        Ok(())
+    }
+
+    pub fn signal_error(&mut self, seqno: u64) -> Result<()> {
+        if let Some(fence) = self.fences.get_mut(&seqno) {
+            fence.signaled = true;
+            fence.error = true;
+            fence.signaled_at = Some(Instant::now());
+        }
+        Ok(())
+    }
+
+    pub fn is_signaled(&self, seqno: u64) -> bool {
+        self.fences.get(&seqno).map_or(false, |f| f.signaled)
+    }
+
+    pub fn wait(&self, seqno: u64, timeout_ms: u64) -> Result<bool> {
+        let deadline = Instant::now() + std::time::Duration::from_millis(timeout_ms);
+        loop {
+            if self.is_signaled(seqno) { return Ok(true); }
+            if Instant::now() > deadline { return Ok(false); }
+            std::hint::spin_loop();
+        }
+    }
+
+    pub fn retire(&mut self, seqno: u64) {
+        self.fences.remove(&seqno);
+    }
+
+    pub fn pending_count(&self) -> usize {
+        self.fences.values().filter(|f| !f.signaled).count()
+    }
+
+    pub fn last_completed(&self) -> u64 {
+        self.fences.values()
+            .filter(|f| f.signaled && !f.error)
+            .map(|f| f.seqno)
+            .max()
+            .unwrap_or(0)
+    }
+}
+
+pub struct WoundWaitMutex {
+    locked_contexts: BTreeMap<u32, Vec<u32>>,
+    ctx_lock_order: Vec<u32>,
+}
+
+impl WoundWaitMutex {
+    pub fn new() -> Self {
+        Self { locked_contexts: BTreeMap::new(), ctx_lock_order: Vec::new() }
+    }
+
+    pub fn acquire(&mut self, ctx_id: u32, objects: &[u32]) -> Result<()> {
+        for &obj in objects {
+            let entry = self.locked_contexts.entry(obj).or_default();
+            if let Some(&owner) = entry.first() {
+                if owner != ctx_id {
+                    if self.ctx_lock_order.iter().position(|&c| c == ctx_id)
+                        < self.ctx_lock_order.iter().position(|&c| c == owner)
+                    {
+                        entry.clear();
+                        entry.push(ctx_id);
+                    } else {
+                        return Err(DriverError::Buffer("ww mutex: would deadlock".into()));
+                    }
+                }
+            } else {
+                entry.push(ctx_id);
+            }
+        }
+        if !self.ctx_lock_order.contains(&ctx_id) {
+            self.ctx_lock_order.push(ctx_id);
+        }
+        Ok(())
+    }
+
+    pub fn release(&mut self, ctx_id: u32, objects: &[u32]) {
+        for obj in objects {
+            if let Some(entry) = self.locked_contexts.get_mut(obj) {
+                entry.retain(|&c| c != ctx_id);
+                if entry.is_empty() {
+                    self.locked_contexts.remove(obj);
+                }
+            }
+        }
+    }
+
+    pub fn locked_objects(&self, ctx_id: u32) -> Vec<u32> {
+        self.locked_contexts.iter()
+            .filter(|(_, owners)| owners.contains(&ctx_id))
+            .map(|(obj, _)| *obj)
+            .collect()
+    }
+}
diff --git a/local/recipes/gpu/redox-drm/source/src/drivers/intel/gem/mod.rs b/local/recipes/gpu/redox-drm/source/src/drivers/intel/gem/mod.rs
index 2963e55899..740b481d8b 100644
--- a/local/recipes/gpu/redox-drm/source/src/drivers/intel/gem/mod.rs
+++ b/local/recipes/gpu/redox-drm/source/src/drivers/intel/gem/mod.rs
@@ -3,6 +3,7 @@ pub mod gem_context;
 pub mod gem_create;
 pub mod gem_dmabuf;
 pub mod gem_domain;
+pub mod gem_evict;
 pub mod gem_execbuffer;
 pub mod gem_init;
 pub mod gem_ioctl;
@@ -22,6 +23,7 @@ pub use gem_context::{ContextManager, ContextPriority, GemContext, create_defaul
 pub use gem_create::{CreateManager, CreateParams};
 pub use gem_dmabuf::{DmaBufExport, DmaBufImport, DmaBufManager};
 pub use gem_domain::{BusyManager, DomainManager, DomainState, GpuDomain, ThrottleManager};
+pub use gem_evict::{EvictableObject, EvictionClass, EvictionManager, FenceObjectManager, GpuFence, WoundWaitMutex};
 pub use gem_execbuffer::{ExecObject, ExecbufferManager, ExecbufferSubmission, RelocationEntry};
 pub use gem_init::{BusyTracker, GemInitManager, RingThrottle, ShrinkerWithEviction, VmaResourceManager};
 pub use gem_ioctl::{FrontbufferState, FrontbufferTracker, UserptrManager, WaitManager};