[PATCH v2] ata: pata_macio: Use WARN instead of BUG

[Michael Ellerman]

The overflow/underflow conditions in pata_macio_qc_prep() should never
happen. But if they do there's no need to kill the system entirely, a
WARN and failing the IO request should be sufficient and might allow the
system to keep running.

Signed-off-by: Michael Ellerman <m...@ellerman.id.au>
---
 drivers/ata/pata_macio.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

v2: Use AC_ERR_SYSTEM as suggested by Damien.

diff --git a/drivers/ata/pata_macio.c b/drivers/ata/pata_macio.c
index 1cb8d24b088f..f2f36e55a1f4 100644
--- a/drivers/ata/pata_macio.c
+++ b/drivers/ata/pata_macio.c
@@ -554,7 +554,8 @@ static enum ata_completion_errors pata_macio_qc_prep(struct 
ata_queued_cmd *qc)
 
                while (sg_len) {
                        /* table overflow should never happen */
-                       BUG_ON (pi++ >= MAX_DCMDS);
+                       if (WARN_ON_ONCE(pi >= MAX_DCMDS))
+                               return AC_ERR_SYSTEM;
 
                        len = (sg_len < MAX_DBDMA_SEG) ? sg_len : MAX_DBDMA_SEG;
                        table->command = cpu_to_le16(write ? OUTPUT_MORE: 
INPUT_MORE);
@@ -566,11 +567,13 @@ static enum ata_completion_errors 
pata_macio_qc_prep(struct ata_queued_cmd *qc)
                        addr += len;
                        sg_len -= len;
                        ++table;
+                       ++pi;
                }
        }
 
        /* Should never happen according to Tejun */
-       BUG_ON(!pi);
+       if (WARN_ON_ONCE(!pi))
+               return AC_ERR_SYSTEM;
 
        /* Convert the last command to an input/output */
        table--;
-- 
2.46.0