spi: Always check complete callback before calling it

Since commit 1e25cd4729bd "spi: Do not require a completion", this checking is
required to prevent NULL pointer dereference.

Signed-off-by: Axel Lin <axel.lin@ingics.com>
Signed-off-by: Mark Brown <broonie@linaro.org>

drivers/spi/spi-fsl-espi.c

@@ -446,7 +446,8 @@ static void fsl_espi_do_one_msg(struct spi_message *m)
 
 	m->actual_length = espi_trans.actual_length;
 	m->status = espi_trans.status;
-	m->complete(m->context);
+	if (m->complete)
+		m->complete(m->context);
 }
 
 static int fsl_espi_setup(struct spi_device *spi)

drivers/spi/spi-fsl-spi.c

@@ -404,7 +404,8 @@ static void fsl_spi_do_one_msg(struct spi_message *m)
 	}
 
 	m->status = status;
-	m->complete(m->context);
+	if (m->complete)
+		m->complete(m->context);
 
 	if (status || !cs_change) {
 		ndelay(nsecs);

drivers/spi/spi-mpc512x-psc.c

@@ -301,7 +301,8 @@ static int mpc512x_psc_spi_msg_xfer(struct spi_master *master,
 	}
 
 	m->status = status;
-	m->complete(m->context);
+	if (m->complete)
+		m->complete(m->context);
 
 	if (status || !cs_change)
 		mpc512x_psc_spi_deactivate_cs(spi);

drivers/spi/spi-mpc52xx-psc.c

@@ -248,7 +248,8 @@ static void mpc52xx_psc_spi_work(struct work_struct *work)
 		}
 
 		m->status = status;
-		m->complete(m->context);
+		if (m->complete)
+			m->complete(m->context);
 
 		if (status || !cs_change)
 			mpc52xx_psc_spi_deactivate_cs(spi);

drivers/spi/spi-mpc52xx.c

@@ -235,7 +235,8 @@ static int mpc52xx_spi_fsmstate_transfer(int irq, struct mpc52xx_spi *ms,
 		dev_err(&ms->master->dev, "mode fault\n");
 		mpc52xx_spi_chipsel(ms, 0);
 		ms->message->status = -EIO;
-		ms->message->complete(ms->message->context);
+		if (ms->message->complete)
+			ms->message->complete(ms->message->context);
 		ms->state = mpc52xx_spi_fsmstate_idle;
 		return FSM_CONTINUE;
 	}
@@ -289,7 +290,8 @@ mpc52xx_spi_fsmstate_wait(int irq, struct mpc52xx_spi *ms, u8 status, u8 data)
 		ms->msg_count++;
 		mpc52xx_spi_chipsel(ms, 0);
 		ms->message->status = 0;
-		ms->message->complete(ms->message->context);
+		if (ms->message->complete)
+			ms->message->complete(ms->message->context);
 		ms->state = mpc52xx_spi_fsmstate_idle;
 		return FSM_CONTINUE;
 	}

drivers/spi/spi-sh.c

@@ -322,7 +322,8 @@ static void spi_sh_work(struct work_struct *work)
 		spin_lock_irqsave(&ss->lock, flags);
 
 		mesg->status = 0;
-		mesg->complete(mesg->context);
+		if (mesg->complete)
+			mesg->complete(mesg->context);
 	}
 
 	clear_fifo(ss);
@@ -340,7 +341,8 @@ static void spi_sh_work(struct work_struct *work)
 
  error:
 	mesg->status = ret;
-	mesg->complete(mesg->context);
+	if (mesg->complete)
+		mesg->complete(mesg->context);
 
 	spi_sh_clear_bit(ss, SPI_SH_SSA | SPI_SH_SSDB | SPI_SH_SSD,
 			 SPI_SH_CR1);

drivers/spi/spi-txx9.c

@@ -265,7 +265,8 @@ static void txx9spi_work_one(struct txx9spi *c, struct spi_message *m)
 
 exit:
 	m->status = status;
-	m->complete(m->context);
+	if (m->complete)
+		m->complete(m->context);
 
 	/* normally deactivate chipselect ... unless no error and
 	 * cs_change has hinted that the next message will probably