linux-kernel - [PATCH 14/15] isci: avoid gcc-10 zero-length-bounds warning

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Date:   Thu, 30 Apr 2020 23:30:56 +0200
From:   Arnd Bergmann <arnd@...db.de>
To:     linux-kernel@...r.kernel.org,
        Intel SCU Linux support <intel-linux-scu@...el.com>,
        Artur Paszkiewicz <artur.paszkiewicz@...el.com>,
        "James E.J. Bottomley" <jejb@...ux.ibm.com>,
        "Martin K. Petersen" <martin.petersen@...cle.com>
Cc:     Arnd Bergmann <arnd@...db.de>, linux-scsi@...r.kernel.org
Subject: [PATCH 14/15] isci: avoid gcc-10 zero-length-bounds warning

gcc-10 warns about accesses to zero-length arrays:

drivers/scsi/isci/task.h:125:31: error: array subscript 0 is outside the bounds of an interior zero-length array 'u8[0]' {aka 'unsigned char[0]'} [-Werror=zero-length-bounds]
  125 |    tmf->resp.resp_iu.resp_data[0],
      |    ~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~
include/linux/dynamic_debug.h:143:2: note: in expansion of macro '__dynamic_func_call'
  143 |  __dynamic_func_call(__UNIQUE_ID(ddebug), fmt, func, ##__VA_ARGS__)
      |  ^~~~~~~~~~~~~~~~~~~
include/linux/dynamic_debug.h:157:2: note: in expansion of macro '_dynamic_func_call'
  157 |  _dynamic_func_call(fmt,__dynamic_dev_dbg,   \
      |  ^~~~~~~~~~~~~~~~~~
include/linux/dev_printk.h:115:2: note: in expansion of macro 'dynamic_dev_dbg'
  115 |  dynamic_dev_dbg(dev, dev_fmt(fmt), ##__VA_ARGS__)
      |  ^~~~~~~~~~~~~~~
drivers/scsi/isci/task.h:111:3: note: in expansion of macro 'dev_dbg'
  111 |   dev_dbg(&ihost->pdev->dev,
      |   ^~~~~~~
In file included from include/scsi/libsas.h:15,
                 from drivers/scsi/isci/task.c:59:
include/scsi/sas.h:326:9: note: while referencing 'resp_data'
  326 |  u8     resp_data[0];
      |         ^~~~~~~~~

This instance is not a bug, so just work around the warning by
adding a temporary pointer.

Signed-off-by: Arnd Bergmann <arnd@...db.de>
---
 drivers/scsi/isci/task.h | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/drivers/scsi/isci/task.h b/drivers/scsi/isci/task.h
index 8f4531f22ac2..2d556d7b5292 100644
--- a/drivers/scsi/isci/task.h
+++ b/drivers/scsi/isci/task.h
@@ -98,6 +98,8 @@ struct isci_tmf {
 
 static inline void isci_print_tmf(struct isci_host *ihost, struct isci_tmf *tmf)
 {
+	u8 *resp = tmf->resp.resp_iu.resp_data;
+
 	if (SAS_PROTOCOL_SATA == tmf->proto)
 		dev_dbg(&ihost->pdev->dev,
 			"%s: status = %x\n"
@@ -122,10 +124,7 @@ static inline void isci_print_tmf(struct isci_host *ihost, struct isci_tmf *tmf)
 			tmf->resp.resp_iu.datapres,
 			tmf->resp.resp_iu.status,
 			be32_to_cpu(tmf->resp.resp_iu.response_data_len),
-			tmf->resp.resp_iu.resp_data[0],
-			tmf->resp.resp_iu.resp_data[1],
-			tmf->resp.resp_iu.resp_data[2],
-			tmf->resp.resp_iu.resp_data[3]);
+			resp[0], resp[1], resp[2], resp[3]);
 }
 
 
-- 
2.26.0