[PATCH AUTOSEL 5.10 3/3] misc: sgi-gru: Don't disable preemption in GRU driver

From: Sasha Levin
Date: Mon Oct 14 2024 - 00:11:53 EST


From: Dimitri Sivanich <sivanich@xxxxxxx>

[ Upstream commit b983b271662bd6104d429b0fd97af3333ba760bf ]

Disabling preemption in the GRU driver is unnecessary, and clashes with
sleeping locks in several code paths. Remove preempt_disable and
preempt_enable from the GRU driver.

Signed-off-by: Dimitri Sivanich <sivanich@xxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
drivers/misc/sgi-gru/grukservices.c | 2 --
drivers/misc/sgi-gru/grumain.c | 4 ----
drivers/misc/sgi-gru/grutlbpurge.c | 2 --
3 files changed, 8 deletions(-)

diff --git a/drivers/misc/sgi-gru/grukservices.c b/drivers/misc/sgi-gru/grukservices.c
index 0ea923fe6371b..e2bdba4742930 100644
--- a/drivers/misc/sgi-gru/grukservices.c
+++ b/drivers/misc/sgi-gru/grukservices.c
@@ -258,7 +258,6 @@ static int gru_get_cpu_resources(int dsr_bytes, void **cb, void **dsr)
int lcpu;

BUG_ON(dsr_bytes > GRU_NUM_KERNEL_DSR_BYTES);
- preempt_disable();
bs = gru_lock_kernel_context(-1);
lcpu = uv_blade_processor_id();
*cb = bs->kernel_cb + lcpu * GRU_HANDLE_STRIDE;
@@ -272,7 +271,6 @@ static int gru_get_cpu_resources(int dsr_bytes, void **cb, void **dsr)
static void gru_free_cpu_resources(void *cb, void *dsr)
{
gru_unlock_kernel_context(uv_numa_blade_id());
- preempt_enable();
}

/*
diff --git a/drivers/misc/sgi-gru/grumain.c b/drivers/misc/sgi-gru/grumain.c
index e2325e3d077ea..4f7a0f8472556 100644
--- a/drivers/misc/sgi-gru/grumain.c
+++ b/drivers/misc/sgi-gru/grumain.c
@@ -941,10 +941,8 @@ vm_fault_t gru_fault(struct vm_fault *vmf)

again:
mutex_lock(&gts->ts_ctxlock);
- preempt_disable();

if (gru_check_context_placement(gts)) {
- preempt_enable();
mutex_unlock(&gts->ts_ctxlock);
gru_unload_context(gts, 1);
return VM_FAULT_NOPAGE;
@@ -953,7 +951,6 @@ vm_fault_t gru_fault(struct vm_fault *vmf)
if (!gts->ts_gru) {
STAT(load_user_context);
if (!gru_assign_gru_context(gts)) {
- preempt_enable();
mutex_unlock(&gts->ts_ctxlock);
set_current_state(TASK_INTERRUPTIBLE);
schedule_timeout(GRU_ASSIGN_DELAY); /* true hack ZZZ */
@@ -969,7 +966,6 @@ vm_fault_t gru_fault(struct vm_fault *vmf)
vma->vm_page_prot);
}

- preempt_enable();
mutex_unlock(&gts->ts_ctxlock);

return VM_FAULT_NOPAGE;
diff --git a/drivers/misc/sgi-gru/grutlbpurge.c b/drivers/misc/sgi-gru/grutlbpurge.c
index 10921cd2608df..1107dd3e2e9fa 100644
--- a/drivers/misc/sgi-gru/grutlbpurge.c
+++ b/drivers/misc/sgi-gru/grutlbpurge.c
@@ -65,7 +65,6 @@ static struct gru_tlb_global_handle *get_lock_tgh_handle(struct gru_state
struct gru_tlb_global_handle *tgh;
int n;

- preempt_disable();
if (uv_numa_blade_id() == gru->gs_blade_id)
n = get_on_blade_tgh(gru);
else
@@ -79,7 +78,6 @@ static struct gru_tlb_global_handle *get_lock_tgh_handle(struct gru_state
static void get_unlock_tgh_handle(struct gru_tlb_global_handle *tgh)
{
unlock_tgh_handle(tgh);
- preempt_enable();
}

/*
--
2.43.0