From 1d2d5753b94b4f6f67044cb6860a2b8d03b2b4b8 Mon Sep 17 00:00:00 2001
From: J Reece Wilson <me@reece.sx>
Date: Tue, 6 Aug 2024 03:22:00 +0100
Subject: [PATCH] [*] Linux: possible regressions in
 57c55151733bd3876a9655dce84984163b72be2d. Fixes read while transaction is
 signaled loops

---
 Source/IO/FS/Async.Linux.cpp      |  2 +-
 Source/IO/UNIX/IOSubmit.Linux.cpp | 86 ++++++++++++++++++++-----------
 2 files changed, 57 insertions(+), 31 deletions(-)

diff --git a/Source/IO/FS/Async.Linux.cpp b/Source/IO/FS/Async.Linux.cpp
index 97d8c57d..d1e8bbeb 100644
--- a/Source/IO/FS/Async.Linux.cpp
+++ b/Source/IO/FS/Async.Linux.cpp
@@ -84,7 +84,7 @@ namespace Aurora::IO::FS
             auto lock = caller_.lock();
             return lock->Complete();
         }
-
+        
         return false;
     }
 
diff --git a/Source/IO/UNIX/IOSubmit.Linux.cpp b/Source/IO/UNIX/IOSubmit.Linux.cpp
index bb7b38f8..10f1eb58 100644
--- a/Source/IO/UNIX/IOSubmit.Linux.cpp
+++ b/Source/IO/UNIX/IOSubmit.Linux.cpp
@@ -645,7 +645,8 @@ namespace Aurora::IO::UNIX
                 (void)LinuxOverlappedTrySubmitWork();
             }
 
-        } while (timeout || AuExchange(bAgain, false));
+        }
+        while (timeout || AuExchange(bAgain, false));
 
         return dwApcsSent;
     }
@@ -661,6 +662,8 @@ namespace Aurora::IO::UNIX
     {
         bool bRet { true };
         timespec targetTime;
+        int iRedoCount {};
+
         auto io = GetTls();
         if (!io)
         {
@@ -698,9 +701,18 @@ namespace Aurora::IO::UNIX
         iocb * ptr = &pollSubmit;
         iocb ** ptrArray = &ptr;
 
-        errno = 0;
-
+        bool bEpollTriggered {};
+        io_event ioEvents[1024];
+        AuTuple<ASubmittable *, AuUInt, bool, int> toProcess[1024] {};
+        int toProcessDone {};
+        int temp {};
+        bool bAgain {};
         int error;
+
+    redo:
+        toProcessDone = 0;
+        bEpollTriggered = false;
+
         do
         {
             error = io_submit(io->context, 1, ptrArray);
@@ -715,18 +727,11 @@ namespace Aurora::IO::UNIX
         {
             SysPushErrorIO();
             return -1;
-        }
-
-        bool bEpollTriggered {};
-        io_event ioEvents[1024];
-        AuTuple<ASubmittable *, AuUInt, bool, int> toProcess[1024] {};
-        int toProcessDone {};
-        int temp {};
-        bool bAgain {};
+        };
 
         do
         {
-            if (timeout)
+            if (timeout && !bAgain)
             {
                 AuUInt64 uTimeNow = AuTime::SteadyClockNS();
                 if (uTargetTime <= uTimeNow)
@@ -800,16 +805,12 @@ namespace Aurora::IO::UNIX
                     SysPanic("io_getevents() is not implemented on this architecture.");                    
                 }
             }
-
-            bAgain = AuExchange(io->bPollHit, false);
-
-            if (bAgain)
-            {
-                (void)LinuxOverlappedTrySubmitWork();
-            }
-        } while ((timeout ? !bEpollTriggered : false) || AuExchange(bAgain, false));
+        }
+        while ((timeout ? !bEpollTriggered : false));
 
     exit:
+        bAgain = false;
+
         io_event finalEpollEvent {};
         if (!bEpollTriggered)
         {
@@ -838,6 +839,15 @@ namespace Aurora::IO::UNIX
             handle->LIOS_SendProcess(bytesTransacted, bError, errNo);
         }
 
+        if ((io->submitPendingArray.size() || (bAgain = AuExchange(io->bPollHit, false))))
+        {
+            LinuxOverlappedTrySubmitWorkInternal(io);
+            if (bAgain && (iRedoCount++) < 4)
+            {
+                goto redo;
+            }
+        }
+
         if (bEpollTriggered)
         {
             return epoll_wait(epfd, events, maxevents, 0);
@@ -855,7 +865,17 @@ namespace Aurora::IO::UNIX
     bool LinuxOverlappedWaitForOne(AuUInt32 timeout, AuUInt read, AuUInt write, bool &bReadTriggered, bool &bWriteTriggered)
     {
         timespec targetTime;
+        iocb submit {};
+        iocb readSubmit {};
+        iocb writeSubmit {};
         bool bRet { true };
+        int iRedoCount {};
+        io_event ioEvents[1024];
+        AuTuple<ASubmittable *, AuUInt, bool, int> toProcess[1024] {};
+        int toProcessDone {};
+        int temp;
+        bool bTryAgain {};
+
         auto io = GetTls();
 
         bWriteTriggered = false;
@@ -886,9 +906,6 @@ namespace Aurora::IO::UNIX
             return false;
         }
 
-        iocb submit {};
-        iocb readSubmit {};
-        iocb writeSubmit {};
         AuMemset(&readSubmit, 0, sizeof(readSubmit));
         AuMemset(&writeSubmit, 0, sizeof(readSubmit));
         AuMemset(&submit, 0, sizeof(submit));
@@ -915,6 +932,8 @@ namespace Aurora::IO::UNIX
             ptrArray[iocbIdx++] = &writeSubmit;
         }
 
+    redo:
+        toProcessDone = 0;
         int error;
         do
         {
@@ -933,14 +952,9 @@ namespace Aurora::IO::UNIX
             return -1;
         }
 
-        io_event ioEvents[1024];
-        AuTuple<ASubmittable *, AuUInt, bool, int> toProcess[1024] {};
-        int toProcessDone {};
-        int temp;
-
         do
         {
-            if (timeout)
+            if (timeout && !bTryAgain)
             {
                 AuUInt64 uTimeNow = AuTime::SteadyClockNS();
                 if (uTargetTime <= uTimeNow)
@@ -1025,9 +1039,12 @@ namespace Aurora::IO::UNIX
                 }
             }
 
-        } while (timeout ? (!bReadTriggered && !bWriteTriggered) : false);
+        }
+        while (timeout ? (!bReadTriggered && !bWriteTriggered) : false);
 
     exit:
+        bTryAgain = false;
+
         for (int i = 0; i < iocbIdx; i++)
         {
             io_event finalEpollEvent {};
@@ -1071,6 +1088,15 @@ namespace Aurora::IO::UNIX
             handle->LIOS_SendProcess(bytesTransacted, bError, errNo);
         }
 
+        if ((io->submitPendingArray.size() || (bTryAgain = AuExchange(io->bPollHit, false))))
+        {
+            LinuxOverlappedTrySubmitWorkInternal(io);
+            if (bTryAgain && (iRedoCount++) < 4)
+            {
+                goto redo;
+            }
+        }
+
         return bRet;
     }