iwlwifi: fix flow handler debug code

iwl_dbgfs_fh_reg_read() can cause crashes and/or
BUG_ON in slub because the ifdefs are wrong, the
code in iwl_dump_fh() should use DEBUGFS, not
DEBUG to protect the buffer writing code.

Also, while at it, clean up the arguments to the
function, some code and make it generally safer.

Cc: stable@vger.kernel.org
Reported-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

3 files changed, 18 insertions, 16 deletions

diff --git a/drivers/net/wireless/iwlwifi/pcie/internal.h b/drivers/net/wireless/iwlwifi/pcie/internal.h
index d9694c58208c..4ffc18dc3a57 100644
--- a/drivers/net/wireless/iwlwifi/pcie/internal.h
+++ b/drivers/net/wireless/iwlwifi/pcie/internal.h
@@ -350,7 +350,7 @@ int iwl_queue_space(const struct iwl_queue *q);
 /*****************************************************
 * Error handling
 ******************************************************/
-int iwl_dump_fh(struct iwl_trans *trans, char **buf, bool display);
+int iwl_dump_fh(struct iwl_trans *trans, char **buf);
 void iwl_dump_csr(struct iwl_trans *trans);
 
 /*****************************************************
diff --git a/drivers/net/wireless/iwlwifi/pcie/rx.c b/drivers/net/wireless/iwlwifi/pcie/rx.c
index 39a6ca1f009c..d1a61ba6247a 100644
--- a/drivers/net/wireless/iwlwifi/pcie/rx.c
+++ b/drivers/net/wireless/iwlwifi/pcie/rx.c
@@ -555,7 +555,7 @@ static void iwl_irq_handle_error(struct iwl_trans *trans)
         }
 
         iwl_dump_csr(trans);
-        iwl_dump_fh(trans, NULL, false);
+        iwl_dump_fh(trans, NULL);
 
         iwl_op_mode_nic_error(trans->op_mode);
 }
diff --git a/drivers/net/wireless/iwlwifi/pcie/trans.c b/drivers/net/wireless/iwlwifi/pcie/trans.c
index 939c2f78df58..1e86ea2266d4 100644
--- a/drivers/net/wireless/iwlwifi/pcie/trans.c
+++ b/drivers/net/wireless/iwlwifi/pcie/trans.c
@@ -1649,13 +1649,9 @@ static const char *get_fh_string(int cmd)
 #undef IWL_CMD
 }
 
-int iwl_dump_fh(struct iwl_trans *trans, char **buf, bool display)
+int iwl_dump_fh(struct iwl_trans *trans, char **buf)
 {
         int i;
-#ifdef CONFIG_IWLWIFI_DEBUG
-        int pos = 0;
-        size_t bufsz = 0;
-#endif
         static const u32 fh_tbl[] = {
                 FH_RSCSR_CHNL0_STTS_WPTR_REG,
                 FH_RSCSR_CHNL0_RBDCB_BASE_REG,
@@ -1667,29 +1663,35 @@ int iwl_dump_fh(struct iwl_trans *trans, char **buf, bool display)
                 FH_TSSR_TX_STATUS_REG,
                 FH_TSSR_TX_ERROR_REG
         };
-#ifdef CONFIG_IWLWIFI_DEBUG
-        if (display) {
-                bufsz = ARRAY_SIZE(fh_tbl) * 48 + 40;
+
+#ifdef CONFIG_IWLWIFI_DEBUGFS
+        if (buf) {
+                int pos = 0;
+                size_t bufsz = ARRAY_SIZE(fh_tbl) * 48 + 40;
+
                 *buf = kmalloc(bufsz, GFP_KERNEL);
                 if (!*buf)
                         return -ENOMEM;
+
                 pos += scnprintf(*buf + pos, bufsz - pos,
                                 "FH register values:\n");
-                for (i = 0; i < ARRAY_SIZE(fh_tbl); i++) {
+
+                for (i = 0; i < ARRAY_SIZE(fh_tbl); i++)
                         pos += scnprintf(*buf + pos, bufsz - pos,
                                 "  %34s: 0X%08x\n",
                                 get_fh_string(fh_tbl[i]),
                                 iwl_read_direct32(trans, fh_tbl[i]));
-                }
+
                 return pos;
         }
 #endif
+
         IWL_ERR(trans, "FH register values:\n");
-        for (i = 0; i <  ARRAY_SIZE(fh_tbl); i++) {
+        for (i = 0; i <  ARRAY_SIZE(fh_tbl); i++)
                 IWL_ERR(trans, "  %34s: 0X%08x\n",
                         get_fh_string(fh_tbl[i]),
                         iwl_read_direct32(trans, fh_tbl[i]));
-        }
+
         return 0;
 }
 
@@ -1982,11 +1984,11 @@ static ssize_t iwl_dbgfs_fh_reg_read(struct file *file,
                                      size_t count, loff_t *ppos)
 {
         struct iwl_trans *trans = file->private_data;
-        char *buf;
+        char *buf = NULL;
         int pos = 0;
         ssize_t ret = -EFAULT;
 
-        ret = pos = iwl_dump_fh(trans, &buf, true);
+        ret = pos = iwl_dump_fh(trans, &buf);
         if (buf) {
                 ret = simple_read_from_buffer(user_buf,
                                               count, ppos, buf, pos);