From 87a59250b5573d770a785f8e915982d304f20172 Mon Sep 17 00:00:00 2001
From: Marcel Moolenaar <marcel@FreeBSD.org>
Date: Fri, 9 Sep 2005 19:18:36 +0000
Subject: [PATCH] Change the High FP lock from a sleep lock to a spin lock. We
 can take the lock from interrupt context, which causes an implicit lock order
 reversal. We've been using the lock carefully enough that making it a spin
 lock should not be harmful.

---
 sys/ia64/ia64/interrupt.c  |  4 ++--
 sys/ia64/ia64/machdep.c    | 14 +++++++-------
 sys/ia64/ia64/trap.c       | 12 ++++++------
 sys/ia64/ia64/vm_machdep.c |  2 +-
 4 files changed, 16 insertions(+), 16 deletions(-)

diff --git a/sys/ia64/ia64/interrupt.c b/sys/ia64/ia64/interrupt.c
index 3e1a12ad4808..0c83d97117f2 100644
--- a/sys/ia64/ia64/interrupt.c
+++ b/sys/ia64/ia64/interrupt.c
@@ -209,11 +209,11 @@ interrupt(u_int64_t vector, struct trapframe *tf)
 	} else if (vector == ipi_vector[IPI_HIGH_FP]) {
 		struct thread *thr = PCPU_GET(fpcurthread);
 		if (thr != NULL) {
-			mtx_lock(&thr->td_md.md_highfp_mtx);
+			mtx_lock_spin(&thr->td_md.md_highfp_mtx);
 			save_high_fp(&thr->td_pcb->pcb_high_fp);
 			thr->td_pcb->pcb_fpcpu = NULL;
 			PCPU_SET(fpcurthread, NULL);
-			mtx_unlock(&thr->td_md.md_highfp_mtx);
+			mtx_unlock_spin(&thr->td_md.md_highfp_mtx);
 		}
 	} else if (vector == ipi_vector[IPI_RENDEZVOUS]) {
 		rdvs[PCPU_GET(cpuid)]++;
diff --git a/sys/ia64/ia64/machdep.c b/sys/ia64/ia64/machdep.c
index 9aa6045d0a48..2baf57dd006c 100644
--- a/sys/ia64/ia64/machdep.c
+++ b/sys/ia64/ia64/machdep.c
@@ -1437,17 +1437,17 @@ ia64_highfp_drop(struct thread *td)
 	struct pcpu *cpu;
 	struct thread *thr;
 
-	mtx_lock(&td->td_md.md_highfp_mtx);
+	mtx_lock_spin(&td->td_md.md_highfp_mtx);
 	pcb = td->td_pcb;
 	cpu = pcb->pcb_fpcpu;
 	if (cpu == NULL) {
-		mtx_unlock(&td->td_md.md_highfp_mtx);
+		mtx_unlock_spin(&td->td_md.md_highfp_mtx);
 		return (0);
 	}
 	pcb->pcb_fpcpu = NULL;
 	thr = cpu->pc_fpcurthread;
 	cpu->pc_fpcurthread = NULL;
-	mtx_unlock(&td->td_md.md_highfp_mtx);
+	mtx_unlock_spin(&td->td_md.md_highfp_mtx);
 
 	/* Post-mortem sanity checking. */
 	KASSERT(thr == td, ("Inconsistent high FP state"));
@@ -1465,18 +1465,18 @@ ia64_highfp_save(struct thread *td)
 	if ((td->td_frame->tf_special.psr & IA64_PSR_MFH) == 0)
 		return (ia64_highfp_drop(td));
 
-	mtx_lock(&td->td_md.md_highfp_mtx);
+	mtx_lock_spin(&td->td_md.md_highfp_mtx);
 	pcb = td->td_pcb;
 	cpu = pcb->pcb_fpcpu;
 	if (cpu == NULL) {
-		mtx_unlock(&td->td_md.md_highfp_mtx);
+		mtx_unlock_spin(&td->td_md.md_highfp_mtx);
 		return (0);
 	}
 #ifdef SMP
 	if (td == curthread)
 		sched_pin();
 	if (cpu != pcpup) {
-		mtx_unlock(&td->td_md.md_highfp_mtx);
+		mtx_unlock_spin(&td->td_md.md_highfp_mtx);
 		ipi_send(cpu, IPI_HIGH_FP);
 		if (td == curthread)
 			sched_unpin();
@@ -1494,7 +1494,7 @@ ia64_highfp_save(struct thread *td)
 	pcb->pcb_fpcpu = NULL;
 	thr = cpu->pc_fpcurthread;
 	cpu->pc_fpcurthread = NULL;
-	mtx_unlock(&td->td_md.md_highfp_mtx);
+	mtx_unlock_spin(&td->td_md.md_highfp_mtx);
 
 	/* Post-mortem sanity cxhecking. */
 	KASSERT(thr == td, ("Inconsistent high FP state"));
diff --git a/sys/ia64/ia64/trap.c b/sys/ia64/ia64/trap.c
index fbb8e13785c1..d68482413912 100644
--- a/sys/ia64/ia64/trap.c
+++ b/sys/ia64/ia64/trap.c
@@ -647,26 +647,26 @@ trap(int vector, struct trapframe *tf)
 			sched_unpin();
 			goto out;
 		} else if (thr != NULL) {
-			mtx_lock(&thr->td_md.md_highfp_mtx);
+			mtx_lock_spin(&thr->td_md.md_highfp_mtx);
 			pcb = thr->td_pcb;
 			save_high_fp(&pcb->pcb_high_fp);
 			pcb->pcb_fpcpu = NULL;
 			PCPU_SET(fpcurthread, NULL);
-			mtx_unlock(&thr->td_md.md_highfp_mtx);
+			mtx_unlock_spin(&thr->td_md.md_highfp_mtx);
 			thr = NULL;
 		}
 
-		mtx_lock(&td->td_md.md_highfp_mtx);
+		mtx_lock_spin(&td->td_md.md_highfp_mtx);
 		pcb = td->td_pcb;
 		pcpu = pcb->pcb_fpcpu;
 
 #ifdef SMP
 		if (pcpu != NULL) {
-			mtx_unlock(&td->td_md.md_highfp_mtx);
+			mtx_unlock_spin(&td->td_md.md_highfp_mtx);
 			ipi_send(pcpu, IPI_HIGH_FP);
 			while (pcb->pcb_fpcpu == pcpu)
 				DELAY(100);
-			mtx_lock(&td->td_md.md_highfp_mtx);
+			mtx_lock_spin(&td->td_md.md_highfp_mtx);
 			pcpu = pcb->pcb_fpcpu;
 			thr = PCPU_GET(fpcurthread);
 		}
@@ -680,7 +680,7 @@ trap(int vector, struct trapframe *tf)
 			tf->tf_special.psr &= ~IA64_PSR_DFH;
 		}
 
-		mtx_unlock(&td->td_md.md_highfp_mtx);
+		mtx_unlock_spin(&td->td_md.md_highfp_mtx);
 		sched_unpin();
 		goto out;
 	}
diff --git a/sys/ia64/ia64/vm_machdep.c b/sys/ia64/ia64/vm_machdep.c
index 8ce6641a9950..c29e9d73fa3f 100644
--- a/sys/ia64/ia64/vm_machdep.c
+++ b/sys/ia64/ia64/vm_machdep.c
@@ -118,7 +118,7 @@ cpu_thread_setup(struct thread *td)
 	sp -= sizeof(struct trapframe);
 	td->td_frame = (struct trapframe *)sp;
 	td->td_frame->tf_length = sizeof(struct trapframe);
-	mtx_init(&td->td_md.md_highfp_mtx, "High FP lock", NULL, MTX_DEF);
+	mtx_init(&td->td_md.md_highfp_mtx, "High FP lock", NULL, MTX_SPIN);
 }
 
 void