[POWERPC] spufs: make state_mutex interruptible

Make most places that use spu_acquire/spu_acquire_saved interruptible,
this allows getting out of the spufs code when e.g. pressing ctrl+c.
There are a few places where we get called e.g. from spufs teardown
routines were we can't simply err out so these are left with a comment.
For now I've also not touched the poll routines because it's open what
libspe would expect in terms of interrupted system calls.
Acked-by: Arnd Bergmann <arnd.bergmann@de.ibm.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jeremy Kerr <jk@ozlabs.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>

arch/powerpc/platforms/cell/spufs/context.c

@@ -106,7 +106,17 @@ int put_spu_context(struct spu_context *ctx)
 void spu_forget(struct spu_context *ctx)
 {
 	struct mm_struct *mm;
-	spu_acquire_saved(ctx);
+
+	/*
+	 * This is basically an open-coded spu_acquire_saved, except that
+	 * we don't acquire the state mutex interruptible.
+	 */
+	mutex_lock(&ctx->state_mutex);
+	if (ctx->state != SPU_STATE_SAVED) {
+		set_bit(SPU_SCHED_WAS_ACTIVE, &ctx->sched_flags);
+		spu_deactivate(ctx);
+	}
+
 	mm = ctx->owner;
 	ctx->owner = NULL;
 	mmput(mm);
@@ -137,13 +147,20 @@ void spu_unmap_mappings(struct spu_context *ctx)
  * spu_acquire_saved - lock spu contex and make sure it is in saved state
  * @ctx:	spu contex to lock
  */
-void spu_acquire_saved(struct spu_context *ctx)
+int spu_acquire_saved(struct spu_context *ctx)
 {
-	spu_acquire(ctx);
+	int ret;
+
+	ret = spu_acquire(ctx);
+	if (ret)
+		return ret;
+
 	if (ctx->state != SPU_STATE_SAVED) {
 		set_bit(SPU_SCHED_WAS_ACTIVE, &ctx->sched_flags);
 		spu_deactivate(ctx);
 	}
+
+	return 0;
 }
 
 /**

arch/powerpc/platforms/cell/spufs/coredump.c

@@ -148,7 +148,9 @@ int spufs_coredump_extra_notes_size(void)
 
 	fd = 0;
 	while ((ctx = coredump_next_context(&fd)) != NULL) {
-		spu_acquire_saved(ctx);
+		rc = spu_acquire_saved(ctx);
+		if (rc)
+			break;
 		rc = spufs_ctx_note_size(ctx, fd);
 		spu_release_saved(ctx);
 		if (rc < 0)
@@ -224,7 +226,9 @@ int spufs_coredump_extra_notes_write(struct file *file, loff_t *foffset)
 
 	fd = 0;
 	while ((ctx = coredump_next_context(&fd)) != NULL) {
-		spu_acquire_saved(ctx);
+		rc = spu_acquire_saved(ctx);
+		if (rc)
+			return rc;
 
 		for (j = 0; spufs_coredump_read[j].name != NULL; j++) {
 			rc = spufs_arch_write_note(ctx, j, file, fd, foffset);

arch/powerpc/platforms/cell/spufs/fault.c

@@ -107,7 +107,7 @@ int spufs_handle_class1(struct spu_context *ctx)
 	u64 ea, dsisr, access;
 	unsigned long flags;
 	unsigned flt = 0;
-	int ret;
+	int ret, ret2;
 
 	/*
 	 * dar and dsisr get passed from the registers
@@ -146,7 +146,14 @@ int spufs_handle_class1(struct spu_context *ctx)
 	if (ret)
 		ret = spu_handle_mm_fault(current->mm, ea, dsisr, &flt);
 
-	spu_acquire(ctx);
+	/*
+	 * If spu_acquire fails due to a pending signal we just want to return
+	 * EINTR to userspace even if that means missing the dma restart or
+	 * updating the page fault statistics.
+	 */
+	ret2 = spu_acquire(ctx);
+	if (ret2)
+		goto out;
 
 	/*
 	 * Clear dsisr under ctxt lock after handling the fault, so that
@@ -177,6 +184,7 @@ int spufs_handle_class1(struct spu_context *ctx)
 	} else
 		spufs_handle_event(ctx, ea, SPE_EVENT_SPE_DATA_STORAGE);
 
+ out:
 	spuctx_switch_state(ctx, SPU_UTIL_SYSTEM);
 	return ret;
 }

arch/powerpc/platforms/cell/spufs/run.c

@@ -292,7 +292,7 @@ static int spu_process_callback(struct spu_context *ctx)
 	u32 ls_pointer, npc;
 	void __iomem *ls;
 	long spu_ret;
-	int ret;
+	int ret, ret2;
 
 	/* get syscall block from local store */
 	npc = ctx->ops->npc_read(ctx) & ~3;
@@ -314,9 +314,11 @@ static int spu_process_callback(struct spu_context *ctx)
 		if (spu_ret <= -ERESTARTSYS) {
 			ret = spu_handle_restartsys(ctx, &spu_ret, &npc);
 		}
-		spu_acquire(ctx);
+		ret2 = spu_acquire(ctx);
 		if (ret == -ERESTARTSYS)
 			return ret;
+		if (ret2)
+			return -EINTR;
 	}
 
 	/* write result, jump over indirect pointer */
@@ -338,7 +340,9 @@ long spufs_run_spu(struct spu_context *ctx, u32 *npc, u32 *event)
 	spu_enable_spu(ctx);
 	ctx->event_return = 0;
 
-	spu_acquire(ctx);
+	ret = spu_acquire(ctx);
+	if (ret)
+		goto out_unlock;
 
 	spu_update_sched_info(ctx);
 
@@ -414,6 +418,7 @@ long spufs_run_spu(struct spu_context *ctx, u32 *npc, u32 *event)
 
 out:
 	*event = ctx->event_return;
+out_unlock:
 	mutex_unlock(&ctx->run_mutex);
 	return ret;
 }

arch/powerpc/platforms/cell/spufs/sched.c

@@ -705,7 +705,9 @@ static void __spu_schedule(struct spu *spu, struct spu_context *ctx)
 
 static void spu_schedule(struct spu *spu, struct spu_context *ctx)
 {
-	spu_acquire(ctx);
+	/* not a candidate for interruptible because it's called either
+	   from the scheduler thread or from spu_deactivate */
+	mutex_lock(&ctx->state_mutex);
 	__spu_schedule(spu, ctx);
 	spu_release(ctx);
 }
@@ -823,7 +825,9 @@ static int __spu_deactivate(struct spu_context *ctx, int force, int max_prio)
 				else {
 					spu_release(ctx);
 					spu_schedule(spu, new);
-					spu_acquire(ctx);
+					/* this one can't easily be made
+					   interruptible */
+					mutex_lock(&ctx->state_mutex);
 				}
 			}
 		}
@@ -867,7 +871,8 @@ static noinline void spusched_tick(struct spu_context *ctx)
 	struct spu *spu = NULL;
 	u32 status;
 
-	spu_acquire(ctx);
+	if (spu_acquire(ctx))
+		BUG();	/* a kernel thread never has signals pending */
 
 	if (ctx->state != SPU_STATE_RUNNABLE)
 		goto out;

arch/powerpc/platforms/cell/spufs/spufs.h

@@ -229,9 +229,9 @@ struct spu *affinity_check(struct spu_context *ctx);
 
 /* context management */
 extern atomic_t nr_spu_contexts;
-static inline void spu_acquire(struct spu_context *ctx)
+static inline int __must_check spu_acquire(struct spu_context *ctx)
 {
-	mutex_lock(&ctx->state_mutex);
+	return mutex_lock_interruptible(&ctx->state_mutex);
 }
 
 static inline void spu_release(struct spu_context *ctx)
@@ -246,7 +246,7 @@ int put_spu_context(struct spu_context *ctx);
 void spu_unmap_mappings(struct spu_context *ctx);
 
 void spu_forget(struct spu_context *ctx);
-void spu_acquire_saved(struct spu_context *ctx);
+int __must_check spu_acquire_saved(struct spu_context *ctx);
 void spu_release_saved(struct spu_context *ctx);
 
 int spu_stopped(struct spu_context *ctx, u32 * stat);
@@ -284,7 +284,9 @@ extern char *isolated_loader;
 		}							\
 		spu_release(ctx);					\
 		schedule();						\
-		spu_acquire(ctx);					\
+		__ret = spu_acquire(ctx);				\
+		if (__ret)						\
+			break;						\
 	}								\
 	finish_wait(&(wq), &__wait);					\
 	__ret;								\