[Patch 11/29] GRU - Handle failures to mmu_notifier_register

steiner
2009-11-24T15:07:55Z

[-- Attachment #1: uv_gru_notifier_fixes --]
[-- Type: text/plain, Size: 4375 bytes --]

From: Jack Steiner <steiner@sgi.com>

Under some conditions, mmu_notifier_register() will fail to register a
mmu_notifier. Fix the GRU driver to correctly handle these failures.

Signed-off-by: Jack Steiner <steiner@sgi.com>

---
drivers/misc/sgi-gru/grufault.c | 6 +++---
drivers/misc/sgi-gru/grumain.c | 18 +++++++++++-------
drivers/misc/sgi-gru/grutlbpurge.c | 8 +++++++-
3 files changed, 21 insertions(+), 11 deletions(-)

Index: linux/drivers/misc/sgi-gru/grufault.c
===================================================================
--- linux.orig/drivers/misc/sgi-gru/grufault.c 2009-11-20 09:32:29.000000000 -0600
+++ linux/drivers/misc/sgi-gru/grufault.c 2009-11-20 09:32:31.000000000 -0600
@@ -96,7 +96,7 @@ static struct gru_thread_state *gru_allo
vma = gru_find_vma(vaddr);
if (vma)
gts = gru_alloc_thread_state(vma, TSID(vaddr, vma));
- if (gts) {
+ if (!IS_ERR(gts)) {
mutex_lock(&gts->ts_ctxlock);
downgrade_write(&mm->mmap_sem);
} else {
@@ -747,8 +747,8 @@ int gru_set_context_option(unsigned long
gru_dbg(grudev, "op %d, gseg 0x%lx, value1 0x%lx\n", req.op, req.gseg, req.val1);

gts = gru_alloc_locked_gts(req.gseg);
- if (!gts)
- return -EINVAL;
+ if (IS_ERR(gts))
+ return PTR_ERR(gts);

switch (req.op) {
case sco_blade_chiplet:
Index: linux/drivers/misc/sgi-gru/grumain.c
===================================================================
--- linux.orig/drivers/misc/sgi-gru/grumain.c 2009-11-20 09:32:29.000000000 -0600
+++ linux/drivers/misc/sgi-gru/grumain.c 2009-11-20 09:32:31.000000000 -0600
@@ -27,6 +27,7 @@
#include <linux/sched.h>
#include <linux/device.h>
#include <linux/list.h>
+#include <linux/err.h>
#include <asm/uv/uv_hub.h>
#include "gru.h"
#include "grutables.h"
@@ -286,7 +287,8 @@ static void gru_unload_mm_tracker(struct
void gts_drop(struct gru_thread_state *gts)
{
if (gts && atomic_dec_return(&gts->ts_refcnt) == 0) {
- gru_drop_mmu_notifier(gts->ts_gms);
+ if (gts->ts_gms)
+ gru_drop_mmu_notifier(gts->ts_gms);
kfree(gts);
STAT(gts_free);
}
@@ -313,13 +315,14 @@ struct gru_thread_state *gru_alloc_gts(s
int cbr_au_count, int dsr_au_count, int options, int tsid)
{
struct gru_thread_state *gts;
+ struct gru_mm_struct *gms;
int bytes;

bytes = DSR_BYTES(dsr_au_count) + CBR_BYTES(cbr_au_count);
bytes += sizeof(struct gru_thread_state);
gts = kmalloc(bytes, GFP_KERNEL);
if (!gts)
- return NULL;
+ return ERR_PTR(-ENOMEM);

STAT(gts_alloc);
memset(gts, 0, sizeof(struct gru_thread_state)); /* zero out header */
@@ -338,9 +341,10 @@ struct gru_thread_state *gru_alloc_gts(s
if (vma) {
gts->ts_mm = current->mm;
gts->ts_vma = vma;
- gts->ts_gms = gru_register_mmu_notifier();
- if (!gts->ts_gms)
+ gms = gru_register_mmu_notifier();
+ if (IS_ERR(gms))
goto err;
+ gts->ts_gms = gms;
}

gru_dbg(grudev, "alloc gts %p\n", gts);
@@ -348,7 +352,7 @@ struct gru_thread_state *gru_alloc_gts(s

err:
gts_drop(gts);
- return NULL;
+ return ERR_CAST(gms);
}

/*
@@ -396,8 +400,8 @@ struct gru_thread_state *gru_alloc_threa

gts = gru_alloc_gts(vma, vdata->vd_cbr_au_count, vdata->vd_dsr_au_count,
vdata->vd_user_options, tsid);
- if (!gts)
- return NULL;
+ if (IS_ERR(gts))
+ return gts;

spin_lock(&vdata->vd_lock);
ngts = gru_find_current_gts_nolock(vdata, tsid);
Index: linux/drivers/misc/sgi-gru/grutlbpurge.c
===================================================================
--- linux.orig/drivers/misc/sgi-gru/grutlbpurge.c 2009-11-20 09:32:14.000000000 -0600
+++ linux/drivers/misc/sgi-gru/grutlbpurge.c 2009-11-20 09:32:31.000000000 -0600
@@ -299,6 +299,7 @@ struct gru_mm_struct *gru_register_mmu_n
{
struct gru_mm_struct *gms;
struct mmu_notifier *mn;
+ int err;

mn = mmu_find_ops(current->mm, &gru_mmuops);
if (mn) {
@@ -311,12 +312,17 @@ struct gru_mm_struct *gru_register_mmu_n
gms->ms_notifier.ops = &gru_mmuops;
atomic_set(&gms->ms_refcnt, 1);
init_waitqueue_head(&gms->ms_wait_queue);
- __mmu_notifier_register(&gms->ms_notifier, current->mm);
+ err = __mmu_notifier_register(&gms->ms_notifier, current->mm);
+ if (err)
+ goto error;
}
}
gru_dbg(grudev, "gms %p, refcnt %d\n", gms,
atomic_read(&gms->ms_refcnt));
return gms;
+error:
+ kfree(gms);
+ return ERR_PTR(err);
}

void gru_drop_mmu_notifier(struct gru_mm_struct *gms)