[PATCH] iwlwifi: mvm: no need to check return value of debugfs_create functions

[PATCH] iwlwifi: mvm: no need to check return value of debugfs_create functions

[Greg Kroah-Hartman]

When calling debugfs functions, there is no need to ever check the
return value.  The function can work or not, but the code logic should
never do something different based on this.

Cc: Johannes Berg <johannes.berg@intel.com>
Cc: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Cc: Luca Coelho <luciano.coelho@intel.com>
Cc: Intel Linux Wireless <linuxwifi@intel.com>
Cc: Kalle Valo <kvalo@codeaurora.org>
Cc: linux-wireless@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 .../wireless/intel/iwlwifi/mvm/debugfs-vif.c  | 17 +---
 .../net/wireless/intel/iwlwifi/mvm/debugfs.c  | 84 +++++++------------
 drivers/net/wireless/intel/iwlwifi/mvm/mvm.h  |  7 +-
 drivers/net/wireless/intel/iwlwifi/mvm/ops.c  | 12 +--
 drivers/net/wireless/intel/iwlwifi/mvm/rs.c   |  8 +-
 5 files changed, 36 insertions(+), 92 deletions(-)

diff --git a/drivers/net/wireless/intel/iwlwifi/mvm/debugfs-vif.c b/drivers/net/wireless/intel/iwlwifi/mvm/debugfs-vif.c
index 33b0af24a537..c52cdc538678 100644
--- a/drivers/net/wireless/intel/iwlwifi/mvm/debugfs-vif.c
+++ b/drivers/net/wireless/intel/iwlwifi/mvm/debugfs-vif.c
@@ -1446,9 +1446,8 @@ static ssize_t iwl_dbgfs_quota_min_read(struct file *file,
 #define MVM_DEBUGFS_READ_WRITE_FILE_OPS(name, bufsz) \
 	_MVM_DEBUGFS_READ_WRITE_FILE_OPS(name, bufsz, struct ieee80211_vif)
 #define MVM_DEBUGFS_ADD_FILE_VIF(name, parent, mode) do {		\
-		if (!debugfs_create_file(#name, mode, parent, vif,	\
-					 &iwl_dbgfs_##name##_ops))	\
-			goto err;					\
+		debugfs_create_file(#name, mode, parent, vif,		\
+				    &iwl_dbgfs_##name##_ops);		\
 	} while (0)
 
 MVM_DEBUGFS_READ_FILE_OPS(mac_params);
@@ -1483,12 +1482,6 @@ void iwl_mvm_vif_dbgfs_register(struct iwl_mvm *mvm, struct ieee80211_vif *vif)
 
 	mvmvif->dbgfs_dir = debugfs_create_dir("iwlmvm", dbgfs_dir);
 
-	if (!mvmvif->dbgfs_dir) {
-		IWL_ERR(mvm, "Failed to create debugfs directory under %pd\n",
-			dbgfs_dir);
-		return;
-	}
-
 	if (iwlmvm_mod_params.power_scheme != IWL_POWER_SCHEME_CAM &&
 	    ((vif->type == NL80211_IFTYPE_STATION && !vif->p2p) ||
 	     (vif->type == NL80211_IFTYPE_STATION && vif->p2p)))
@@ -1537,12 +1530,6 @@ void iwl_mvm_vif_dbgfs_register(struct iwl_mvm *mvm, struct ieee80211_vif *vif)
 
 	mvmvif->dbgfs_slink = debugfs_create_symlink(dbgfs_dir->d_name.name,
 						     mvm->debugfs_dir, buf);
-	if (!mvmvif->dbgfs_slink)
-		IWL_ERR(mvm, "Can't create debugfs symbolic link under %pd\n",
-			dbgfs_dir);
-	return;
-err:
-	IWL_ERR(mvm, "Can't create debugfs entity\n");
 }
 
 void iwl_mvm_vif_dbgfs_clean(struct iwl_mvm *mvm, struct ieee80211_vif *vif)
diff --git a/drivers/net/wireless/intel/iwlwifi/mvm/debugfs.c b/drivers/net/wireless/intel/iwlwifi/mvm/debugfs.c
index 52c361a6124c..adecd6d78d6f 100644
--- a/drivers/net/wireless/intel/iwlwifi/mvm/debugfs.c
+++ b/drivers/net/wireless/intel/iwlwifi/mvm/debugfs.c
@@ -1631,9 +1631,8 @@ static ssize_t iwl_dbgfs_d0i3_refs_write(struct iwl_mvm *mvm, char *buf,
 #define MVM_DEBUGFS_READ_WRITE_FILE_OPS(name, bufsz) \
 	_MVM_DEBUGFS_READ_WRITE_FILE_OPS(name, bufsz, struct iwl_mvm)
 #define MVM_DEBUGFS_ADD_FILE_ALIAS(alias, name, parent, mode) do {	\
-		if (!debugfs_create_file(alias, mode, parent, mvm,	\
-					 &iwl_dbgfs_##name##_ops))	\
-			goto err;					\
+		debugfs_create_file(alias, mode, parent, mvm,		\
+				    &iwl_dbgfs_##name##_ops);		\
 	} while (0)
 #define MVM_DEBUGFS_ADD_FILE(name, parent, mode) \
 	MVM_DEBUGFS_ADD_FILE_ALIAS(#name, name, parent, mode)
@@ -1644,9 +1643,8 @@ static ssize_t iwl_dbgfs_d0i3_refs_write(struct iwl_mvm *mvm, char *buf,
 	_MVM_DEBUGFS_READ_WRITE_FILE_OPS(name, bufsz, struct ieee80211_sta)
 
 #define MVM_DEBUGFS_ADD_STA_FILE_ALIAS(alias, name, parent, mode) do {	\
-		if (!debugfs_create_file(alias, mode, parent, sta,	\
-					 &iwl_dbgfs_##name##_ops))	\
-			goto err;					\
+		debugfs_create_file(alias, mode, parent, sta,		\
+				    &iwl_dbgfs_##name##_ops);		\
 	} while (0)
 #define MVM_DEBUGFS_ADD_STA_FILE(name, parent, mode) \
 	MVM_DEBUGFS_ADD_STA_FILE_ALIAS(#name, name, parent, mode)
@@ -1963,13 +1961,9 @@ void iwl_mvm_sta_add_debugfs(struct ieee80211_hw *hw,
 
 	if (iwl_mvm_has_tlc_offload(mvm))
 		MVM_DEBUGFS_ADD_STA_FILE(rs_data, dir, 0400);
-
-	return;
-err:
-	IWL_ERR(mvm, "Can't create the mvm station debugfs entry\n");
 }
 
-int iwl_mvm_dbgfs_register(struct iwl_mvm *mvm, struct dentry *dbgfs_dir)
+void iwl_mvm_dbgfs_register(struct iwl_mvm *mvm, struct dentry *dbgfs_dir)
 {
 	struct dentry *bcast_dir __maybe_unused;
 	char buf[100];
@@ -2012,14 +2006,10 @@ int iwl_mvm_dbgfs_register(struct iwl_mvm *mvm, struct dentry *dbgfs_dir)
 #endif
 	MVM_DEBUGFS_ADD_FILE(he_sniffer_params, mvm->debugfs_dir, 0200);
 
-	if (!debugfs_create_bool("enable_scan_iteration_notif",
-				 0600,
-				 mvm->debugfs_dir,
-				 &mvm->scan_iter_notif_enabled))
-		goto err;
-	if (!debugfs_create_bool("drop_bcn_ap_mode", 0600,
-				 mvm->debugfs_dir, &mvm->drop_bcn_ap_mode))
-		goto err;
+	debugfs_create_bool("enable_scan_iteration_notif", 0600,
+			    mvm->debugfs_dir, &mvm->scan_iter_notif_enabled);
+	debugfs_create_bool("drop_bcn_ap_mode", 0600, mvm->debugfs_dir,
+			    &mvm->drop_bcn_ap_mode);
 
 	MVM_DEBUGFS_ADD_FILE(uapsd_noagg_bssids, mvm->debugfs_dir, S_IRUSR);
 
@@ -2027,13 +2017,9 @@ int iwl_mvm_dbgfs_register(struct iwl_mvm *mvm, struct dentry *dbgfs_dir)
 	if (mvm->fw->ucode_capa.flags & IWL_UCODE_TLV_FLAGS_BCAST_FILTERING) {
 		bcast_dir = debugfs_create_dir("bcast_filtering",
 					       mvm->debugfs_dir);
-		if (!bcast_dir)
-			goto err;
 
-		if (!debugfs_create_bool("override", 0600,
-					 bcast_dir,
-					 &mvm->dbgfs_bcast_filtering.override))
-			goto err;
+		debugfs_create_bool("override", 0600, bcast_dir,
+				    &mvm->dbgfs_bcast_filtering.override);
 
 		MVM_DEBUGFS_ADD_FILE_ALIAS("filters", bcast_filters,
 					   bcast_dir, 0600);
@@ -2045,32 +2031,24 @@ int iwl_mvm_dbgfs_register(struct iwl_mvm *mvm, struct dentry *dbgfs_dir)
 #ifdef CONFIG_PM_SLEEP
 	MVM_DEBUGFS_ADD_FILE(d3_sram, mvm->debugfs_dir, 0600);
 	MVM_DEBUGFS_ADD_FILE(d3_test, mvm->debugfs_dir, 0400);
-	if (!debugfs_create_bool("d3_wake_sysassert", 0600,
-				 mvm->debugfs_dir, &mvm->d3_wake_sysassert))
-		goto err;
-	if (!debugfs_create_u32("last_netdetect_scans", 0400,
-				mvm->debugfs_dir, &mvm->last_netdetect_scans))
-		goto err;
+	debugfs_create_bool("d3_wake_sysassert", 0600, mvm->debugfs_dir,
+			    &mvm->d3_wake_sysassert);
+	debugfs_create_u32("last_netdetect_scans", 0400, mvm->debugfs_dir,
+			   &mvm->last_netdetect_scans);
 #endif
 
-	if (!debugfs_create_u8("ps_disabled", 0400,
-			       mvm->debugfs_dir, &mvm->ps_disabled))
-		goto err;
-	if (!debugfs_create_blob("nvm_hw", 0400,
-				 mvm->debugfs_dir, &mvm->nvm_hw_blob))
-		goto err;
-	if (!debugfs_create_blob("nvm_sw", 0400,
-				 mvm->debugfs_dir, &mvm->nvm_sw_blob))
-		goto err;
-	if (!debugfs_create_blob("nvm_calib", 0400,
-				 mvm->debugfs_dir, &mvm->nvm_calib_blob))
-		goto err;
-	if (!debugfs_create_blob("nvm_prod", 0400,
-				 mvm->debugfs_dir, &mvm->nvm_prod_blob))
-		goto err;
-	if (!debugfs_create_blob("nvm_phy_sku", 0400,
-				 mvm->debugfs_dir, &mvm->nvm_phy_sku_blob))
-		goto err;
+	debugfs_create_u8("ps_disabled", 0400, mvm->debugfs_dir,
+			  &mvm->ps_disabled);
+	debugfs_create_blob("nvm_hw", 0400, mvm->debugfs_dir,
+			    &mvm->nvm_hw_blob);
+	debugfs_create_blob("nvm_sw", 0400, mvm->debugfs_dir,
+			    &mvm->nvm_sw_blob);
+	debugfs_create_blob("nvm_calib", 0400, mvm->debugfs_dir,
+			    &mvm->nvm_calib_blob);
+	debugfs_create_blob("nvm_prod", 0400, mvm->debugfs_dir,
+			    &mvm->nvm_prod_blob);
+	debugfs_create_blob("nvm_phy_sku", 0400, mvm->debugfs_dir,
+			    &mvm->nvm_phy_sku_blob);
 
 	debugfs_create_file("mem", 0600, dbgfs_dir, mvm, &iwl_dbgfs_mem_ops);
 
@@ -2079,11 +2057,5 @@ int iwl_mvm_dbgfs_register(struct iwl_mvm *mvm, struct dentry *dbgfs_dir)
 	 * exists (before the opmode exists which removes the target.)
 	 */
 	snprintf(buf, 100, "../../%pd2", dbgfs_dir->d_parent);
-	if (!debugfs_create_symlink("iwlwifi", mvm->hw->wiphy->debugfsdir, buf))
-		goto err;
-
-	return 0;
-err:
-	IWL_ERR(mvm, "Can't create the mvm debugfs directory\n");
-	return -ENOMEM;
+	debugfs_create_symlink("iwlwifi", mvm->hw->wiphy->debugfsdir, buf);
 }
diff --git a/drivers/net/wireless/intel/iwlwifi/mvm/mvm.h b/drivers/net/wireless/intel/iwlwifi/mvm/mvm.h
index 1aa690e081ff..565a6158634a 100644
--- a/drivers/net/wireless/intel/iwlwifi/mvm/mvm.h
+++ b/drivers/net/wireless/intel/iwlwifi/mvm/mvm.h
@@ -1682,14 +1682,13 @@ void iwl_mvm_rx_umac_scan_iter_complete_notif(struct iwl_mvm *mvm,
 
 /* MVM debugfs */
 #ifdef CONFIG_IWLWIFI_DEBUGFS
-int iwl_mvm_dbgfs_register(struct iwl_mvm *mvm, struct dentry *dbgfs_dir);
+void iwl_mvm_dbgfs_register(struct iwl_mvm *mvm, struct dentry *dbgfs_dir);
 void iwl_mvm_vif_dbgfs_register(struct iwl_mvm *mvm, struct ieee80211_vif *vif);
 void iwl_mvm_vif_dbgfs_clean(struct iwl_mvm *mvm, struct ieee80211_vif *vif);
 #else
-static inline int iwl_mvm_dbgfs_register(struct iwl_mvm *mvm,
-					 struct dentry *dbgfs_dir)
+static inline void iwl_mvm_dbgfs_register(struct iwl_mvm *mvm,
+					  struct dentry *dbgfs_dir)
 {
-	return 0;
 }
 static inline void
 iwl_mvm_vif_dbgfs_register(struct iwl_mvm *mvm, struct ieee80211_vif *vif)
diff --git a/drivers/net/wireless/intel/iwlwifi/mvm/ops.c b/drivers/net/wireless/intel/iwlwifi/mvm/ops.c
index 30c5127034a0..c16edcd17470 100644
--- a/drivers/net/wireless/intel/iwlwifi/mvm/ops.c
+++ b/drivers/net/wireless/intel/iwlwifi/mvm/ops.c
@@ -827,9 +827,7 @@ iwl_op_mode_mvm_start(struct iwl_trans *trans, const struct iwl_cfg *cfg,
 	min_backoff = iwl_mvm_min_backoff(mvm);
 	iwl_mvm_thermal_initialize(mvm, min_backoff);
 
-	err = iwl_mvm_dbgfs_register(mvm, dbgfs_dir);
-	if (err)
-		goto out_unregister;
+	iwl_mvm_dbgfs_register(mvm, dbgfs_dir);
 
 	if (!iwl_mvm_has_new_rx_stats_api(mvm))
 		memset(&mvm->rx_stats_v3, 0,
@@ -848,14 +846,6 @@ iwl_op_mode_mvm_start(struct iwl_trans *trans, const struct iwl_cfg *cfg,
 
 	return op_mode;
 
- out_unregister:
-	if (iwlmvm_mod_params.init_dbg)
-		return op_mode;
-
-	ieee80211_unregister_hw(mvm->hw);
-	mvm->hw_registered = false;
-	iwl_mvm_leds_exit(mvm);
-	iwl_mvm_thermal_exit(mvm);
  out_free:
 	iwl_fw_flush_dump(&mvm->fwrt);
 	iwl_fw_runtime_free(&mvm->fwrt);
diff --git a/drivers/net/wireless/intel/iwlwifi/mvm/rs.c b/drivers/net/wireless/intel/iwlwifi/mvm/rs.c
index 089972280daa..0402e235160e 100644
--- a/drivers/net/wireless/intel/iwlwifi/mvm/rs.c
+++ b/drivers/net/wireless/intel/iwlwifi/mvm/rs.c
@@ -4041,9 +4041,8 @@ static ssize_t iwl_dbgfs_ss_force_write(struct iwl_lq_sta *lq_sta, char *buf,
 #define MVM_DEBUGFS_READ_WRITE_FILE_OPS(name, bufsz) \
 	_MVM_DEBUGFS_READ_WRITE_FILE_OPS(name, bufsz, struct iwl_lq_sta)
 #define MVM_DEBUGFS_ADD_FILE_RS(name, parent, mode) do {		\
-		if (!debugfs_create_file(#name, mode, parent, lq_sta,	\
-					 &iwl_dbgfs_##name##_ops))	\
-			goto err;					\
+		debugfs_create_file(#name, mode, parent, lq_sta,	\
+				    &iwl_dbgfs_##name##_ops);		\
 	} while (0)
 
 MVM_DEBUGFS_READ_WRITE_FILE_OPS(ss_force, 32);
@@ -4071,9 +4070,6 @@ static void rs_drv_add_sta_debugfs(void *mvm, void *priv_sta,
 			  &lq_sta->pers.dbg_fixed_txp_reduction);
 
 	MVM_DEBUGFS_ADD_FILE_RS(ss_force, dir, 0600);
-	return;
-err:
-	IWL_ERR((struct iwl_mvm *)mvm, "Can't create debugfs entity\n");
 }
 
 void rs_remove_sta_debugfs(void *mvm, void *mvm_sta)
-- 
2.20.1

Re: [PATCH] iwlwifi: mvm: no need to check return value of debugfs_create functions

[Luciano Coelho]

On Tue, 2019-01-22 at 16:21 +0100, Greg Kroah-Hartman wrote:
> When calling debugfs functions, there is no need to ever check the
> return value.  The function can work or not, but the code logic
> should
> never do something different based on this.
> 
> Cc: Johannes Berg <johannes.berg@intel.com>
> Cc: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
> Cc: Luca Coelho <luciano.coelho@intel.com>
> Cc: Intel Linux Wireless <linuxwifi@intel.com>
> Cc: Kalle Valo <kvalo@codeaurora.org>
> Cc: linux-wireless@vger.kernel.org
> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> ---


Thanks, Greg! I applied this in our internal tree and it will reach
upstream following our normal upstreaming process.

--
Cheers,
Luca.

Re: [PATCH] iwlwifi: mvm: no need to check return value of debugfs_create functions

[Laura Abbott]

On 1/22/19 7:21 AM, Greg Kroah-Hartman wrote:
> diff --git a/drivers/net/wireless/intel/iwlwifi/mvm/debugfs-vif.c b/drivers/net/wireless/intel/iwlwifi/mvm/debugfs-vif.c
> index 33b0af24a537..c52cdc538678 100644
> --- a/drivers/net/wireless/intel/iwlwifi/mvm/debugfs-vif.c
> +++ b/drivers/net/wireless/intel/iwlwifi/mvm/debugfs-vif.c
> @@ -1446,9 +1446,8 @@ static ssize_t iwl_dbgfs_quota_min_read(struct file *file,
>   #define MVM_DEBUGFS_READ_WRITE_FILE_OPS(name, bufsz) \
>   	_MVM_DEBUGFS_READ_WRITE_FILE_OPS(name, bufsz, struct ieee80211_vif)
>   #define MVM_DEBUGFS_ADD_FILE_VIF(name, parent, mode) do {		\
> -		if (!debugfs_create_file(#name, mode, parent, vif,	\
> -					 &iwl_dbgfs_##name##_ops))	\
> -			goto err;					\
> +		debugfs_create_file(#name, mode, parent, vif,		\
> +				    &iwl_dbgfs_##name##_ops);		\
>   	} while (0)
>   
>   MVM_DEBUGFS_READ_FILE_OPS(mac_params);
> @@ -1483,12 +1482,6 @@ void iwl_mvm_vif_dbgfs_register(struct iwl_mvm *mvm, struct ieee80211_vif *vif)
>   
>   	mvmvif->dbgfs_dir = debugfs_create_dir("iwlmvm", dbgfs_dir);
>   
> -	if (!mvmvif->dbgfs_dir) {
> -		IWL_ERR(mvm, "Failed to create debugfs directory under %pd\n",
> -			dbgfs_dir);
> -		return;
> -	}
> -
>   	if (iwlmvm_mod_params.power_scheme != IWL_POWER_SCHEME_CAM &&
>   	    ((vif->type == NL80211_IFTYPE_STATION && !vif->p2p) ||
>   	     (vif->type == NL80211_IFTYPE_STATION && vif->p2p)))
> @@ -1537,12 +1530,6 @@ void iwl_mvm_vif_dbgfs_register(struct iwl_mvm *mvm, struct ieee80211_vif *vif)
>   
>   	mvmvif->dbgfs_slink = debugfs_create_symlink(dbgfs_dir->d_name.name,
>   						     mvm->debugfs_dir, buf);
> -	if (!mvmvif->dbgfs_slink)
> -		IWL_ERR(mvm, "Can't create debugfs symbolic link under %pd\n",
> -			dbgfs_dir);
> -	return;
> -err:
> -	IWL_ERR(mvm, "Can't create debugfs entity\n");
>   }
>   

Fedora got a bug report https://bugzilla.redhat.com/show_bug.cgi?id=1691034
of a crash with 5.0 and the user did a bisect which pointed to ff9fb72bc077
("debugfs: return error values, not NULL") because the error checking is
no longer correct in this driver.

Based on https://patchwork.kernel.org/patch/10865839/, it looks like
this is supposed to go in for 5.2 but this needs to go in now as
the error checking is currently broken without it. Can this get queued
for Linus so we can get it in 5.0 stable?

Thanks,
Laura

Re: [PATCH] iwlwifi: mvm: no need to check return value of debugfs_create functions

[Greg Kroah-Hartman]

On Tue, Mar 26, 2019 at 04:55:54PM -0700, Laura Abbott wrote:
> On 1/22/19 7:21 AM, Greg Kroah-Hartman wrote:
> > diff --git a/drivers/net/wireless/intel/iwlwifi/mvm/debugfs-vif.c b/drivers/net/wireless/intel/iwlwifi/mvm/debugfs-vif.c
> > index 33b0af24a537..c52cdc538678 100644
> > --- a/drivers/net/wireless/intel/iwlwifi/mvm/debugfs-vif.c
> > +++ b/drivers/net/wireless/intel/iwlwifi/mvm/debugfs-vif.c
> > @@ -1446,9 +1446,8 @@ static ssize_t iwl_dbgfs_quota_min_read(struct file *file,
> >   #define MVM_DEBUGFS_READ_WRITE_FILE_OPS(name, bufsz) \
> >   	_MVM_DEBUGFS_READ_WRITE_FILE_OPS(name, bufsz, struct ieee80211_vif)
> >   #define MVM_DEBUGFS_ADD_FILE_VIF(name, parent, mode) do {		\
> > -		if (!debugfs_create_file(#name, mode, parent, vif,	\
> > -					 &iwl_dbgfs_##name##_ops))	\
> > -			goto err;					\
> > +		debugfs_create_file(#name, mode, parent, vif,		\
> > +				    &iwl_dbgfs_##name##_ops);		\
> >   	} while (0)
> >   MVM_DEBUGFS_READ_FILE_OPS(mac_params);
> > @@ -1483,12 +1482,6 @@ void iwl_mvm_vif_dbgfs_register(struct iwl_mvm *mvm, struct ieee80211_vif *vif)
> >   	mvmvif->dbgfs_dir = debugfs_create_dir("iwlmvm", dbgfs_dir);
> > -	if (!mvmvif->dbgfs_dir) {
> > -		IWL_ERR(mvm, "Failed to create debugfs directory under %pd\n",
> > -			dbgfs_dir);
> > -		return;
> > -	}
> > -
> >   	if (iwlmvm_mod_params.power_scheme != IWL_POWER_SCHEME_CAM &&
> >   	    ((vif->type == NL80211_IFTYPE_STATION && !vif->p2p) ||
> >   	     (vif->type == NL80211_IFTYPE_STATION && vif->p2p)))
> > @@ -1537,12 +1530,6 @@ void iwl_mvm_vif_dbgfs_register(struct iwl_mvm *mvm, struct ieee80211_vif *vif)
> >   	mvmvif->dbgfs_slink = debugfs_create_symlink(dbgfs_dir->d_name.name,
> >   						     mvm->debugfs_dir, buf);
> > -	if (!mvmvif->dbgfs_slink)
> > -		IWL_ERR(mvm, "Can't create debugfs symbolic link under %pd\n",
> > -			dbgfs_dir);
> > -	return;
> > -err:
> > -	IWL_ERR(mvm, "Can't create debugfs entity\n");
> >   }
> 
> Fedora got a bug report https://bugzilla.redhat.com/show_bug.cgi?id=1691034
> of a crash with 5.0 and the user did a bisect which pointed to ff9fb72bc077
> ("debugfs: return error values, not NULL") because the error checking is
> no longer correct in this driver.
> 
> Based on https://patchwork.kernel.org/patch/10865839/, it looks like
> this is supposed to go in for 5.2 but this needs to go in now as
> the error checking is currently broken without it. Can this get queued
> for Linus so we can get it in 5.0 stable?

That's odd, I can't see how the error checking is wrong here.  If the
directory is not created, an error will be returned, which should be
able to be handled by debugfs_create_file().

So with this patch does the error go away?

strange,

greg k-h

Re: [PATCH] iwlwifi: mvm: no need to check return value of debugfs_create functions

[Laura Abbott]

On 3/26/19 6:26 PM, Greg Kroah-Hartman wrote:
> On Tue, Mar 26, 2019 at 04:55:54PM -0700, Laura Abbott wrote:
>> On 1/22/19 7:21 AM, Greg Kroah-Hartman wrote:
>>> diff --git a/drivers/net/wireless/intel/iwlwifi/mvm/debugfs-vif.c b/drivers/net/wireless/intel/iwlwifi/mvm/debugfs-vif.c
>>> index 33b0af24a537..c52cdc538678 100644
>>> --- a/drivers/net/wireless/intel/iwlwifi/mvm/debugfs-vif.c
>>> +++ b/drivers/net/wireless/intel/iwlwifi/mvm/debugfs-vif.c
>>> @@ -1446,9 +1446,8 @@ static ssize_t iwl_dbgfs_quota_min_read(struct file *file,
>>>    #define MVM_DEBUGFS_READ_WRITE_FILE_OPS(name, bufsz) \
>>>    	_MVM_DEBUGFS_READ_WRITE_FILE_OPS(name, bufsz, struct ieee80211_vif)
>>>    #define MVM_DEBUGFS_ADD_FILE_VIF(name, parent, mode) do {		\
>>> -		if (!debugfs_create_file(#name, mode, parent, vif,	\
>>> -					 &iwl_dbgfs_##name##_ops))	\
>>> -			goto err;					\
>>> +		debugfs_create_file(#name, mode, parent, vif,		\
>>> +				    &iwl_dbgfs_##name##_ops);		\
>>>    	} while (0)
>>>    MVM_DEBUGFS_READ_FILE_OPS(mac_params);
>>> @@ -1483,12 +1482,6 @@ void iwl_mvm_vif_dbgfs_register(struct iwl_mvm *mvm, struct ieee80211_vif *vif)
>>>    	mvmvif->dbgfs_dir = debugfs_create_dir("iwlmvm", dbgfs_dir);
>>> -	if (!mvmvif->dbgfs_dir) {
>>> -		IWL_ERR(mvm, "Failed to create debugfs directory under %pd\n",
>>> -			dbgfs_dir);
>>> -		return;
>>> -	}
>>> -
>>>    	if (iwlmvm_mod_params.power_scheme != IWL_POWER_SCHEME_CAM &&
>>>    	    ((vif->type == NL80211_IFTYPE_STATION && !vif->p2p) ||
>>>    	     (vif->type == NL80211_IFTYPE_STATION && vif->p2p)))
>>> @@ -1537,12 +1530,6 @@ void iwl_mvm_vif_dbgfs_register(struct iwl_mvm *mvm, struct ieee80211_vif *vif)
>>>    	mvmvif->dbgfs_slink = debugfs_create_symlink(dbgfs_dir->d_name.name,
>>>    						     mvm->debugfs_dir, buf);
>>> -	if (!mvmvif->dbgfs_slink)
>>> -		IWL_ERR(mvm, "Can't create debugfs symbolic link under %pd\n",
>>> -			dbgfs_dir);
>>> -	return;
>>> -err:
>>> -	IWL_ERR(mvm, "Can't create debugfs entity\n");
>>>    }
>>
>> Fedora got a bug report https://bugzilla.redhat.com/show_bug.cgi?id=1691034
>> of a crash with 5.0 and the user did a bisect which pointed to ff9fb72bc077
>> ("debugfs: return error values, not NULL") because the error checking is
>> no longer correct in this driver.
>>
>> Based on https://patchwork.kernel.org/patch/10865839/, it looks like
>> this is supposed to go in for 5.2 but this needs to go in now as
>> the error checking is currently broken without it. Can this get queued
>> for Linus so we can get it in 5.0 stable?
> 
> That's odd, I can't see how the error checking is wrong here.  If the
> directory is not created, an error will be returned, which should be
> able to be handled by debugfs_create_file().
> 
> So with this patch does the error go away?
> 

The full patch didn't apply cleanly and I didn't try to backport it
for the reporter to test. I was going off of the theory that if the
patch was there it would fix the problem.

What I _think_ is going wrong is dbgfs_dir is actually an errno value:


         struct dentry *dbgfs_dir = vif->debugfs_dir;
         struct iwl_mvm_vif *mvmvif = iwl_mvm_vif_from_mac80211(vif);
         char buf[100];

         /*
          * Check if debugfs directory already exist before creating it.
          * This may happen when, for example, resetting hw or suspend-resume
          */
         if (!dbgfs_dir || mvmvif->dbgfs_dir)
                 return;


so this blows up in the snprintf

         snprintf(buf, 100, "../../../%pd3/%pd",
                  dbgfs_dir,
                  mvmvif->dbgfs_dir);

Unless I misunderstood what the debugfs error change did. I think this
also means the if check needs to look for IS_ERR and not just !dbgfs_dir.

Thanks,
Laura

> strange,
> 
> greg k-h
> 

Re: [PATCH] iwlwifi: mvm: no need to check return value of debugfs_create functions

[Greg Kroah-Hartman]

On Tue, Mar 26, 2019 at 06:47:33PM -0700, Laura Abbott wrote:
> On 3/26/19 6:26 PM, Greg Kroah-Hartman wrote:
> > On Tue, Mar 26, 2019 at 04:55:54PM -0700, Laura Abbott wrote:
> > > On 1/22/19 7:21 AM, Greg Kroah-Hartman wrote:
> > > > diff --git a/drivers/net/wireless/intel/iwlwifi/mvm/debugfs-vif.c b/drivers/net/wireless/intel/iwlwifi/mvm/debugfs-vif.c
> > > > index 33b0af24a537..c52cdc538678 100644
> > > > --- a/drivers/net/wireless/intel/iwlwifi/mvm/debugfs-vif.c
> > > > +++ b/drivers/net/wireless/intel/iwlwifi/mvm/debugfs-vif.c
> > > > @@ -1446,9 +1446,8 @@ static ssize_t iwl_dbgfs_quota_min_read(struct file *file,
> > > >    #define MVM_DEBUGFS_READ_WRITE_FILE_OPS(name, bufsz) \
> > > >    	_MVM_DEBUGFS_READ_WRITE_FILE_OPS(name, bufsz, struct ieee80211_vif)
> > > >    #define MVM_DEBUGFS_ADD_FILE_VIF(name, parent, mode) do {		\
> > > > -		if (!debugfs_create_file(#name, mode, parent, vif,	\
> > > > -					 &iwl_dbgfs_##name##_ops))	\
> > > > -			goto err;					\
> > > > +		debugfs_create_file(#name, mode, parent, vif,		\
> > > > +				    &iwl_dbgfs_##name##_ops);		\
> > > >    	} while (0)
> > > >    MVM_DEBUGFS_READ_FILE_OPS(mac_params);
> > > > @@ -1483,12 +1482,6 @@ void iwl_mvm_vif_dbgfs_register(struct iwl_mvm *mvm, struct ieee80211_vif *vif)
> > > >    	mvmvif->dbgfs_dir = debugfs_create_dir("iwlmvm", dbgfs_dir);
> > > > -	if (!mvmvif->dbgfs_dir) {
> > > > -		IWL_ERR(mvm, "Failed to create debugfs directory under %pd\n",
> > > > -			dbgfs_dir);
> > > > -		return;
> > > > -	}
> > > > -
> > > >    	if (iwlmvm_mod_params.power_scheme != IWL_POWER_SCHEME_CAM &&
> > > >    	    ((vif->type == NL80211_IFTYPE_STATION && !vif->p2p) ||
> > > >    	     (vif->type == NL80211_IFTYPE_STATION && vif->p2p)))
> > > > @@ -1537,12 +1530,6 @@ void iwl_mvm_vif_dbgfs_register(struct iwl_mvm *mvm, struct ieee80211_vif *vif)
> > > >    	mvmvif->dbgfs_slink = debugfs_create_symlink(dbgfs_dir->d_name.name,
> > > >    						     mvm->debugfs_dir, buf);
> > > > -	if (!mvmvif->dbgfs_slink)
> > > > -		IWL_ERR(mvm, "Can't create debugfs symbolic link under %pd\n",
> > > > -			dbgfs_dir);
> > > > -	return;
> > > > -err:
> > > > -	IWL_ERR(mvm, "Can't create debugfs entity\n");
> > > >    }
> > > 
> > > Fedora got a bug report https://bugzilla.redhat.com/show_bug.cgi?id=1691034
> > > of a crash with 5.0 and the user did a bisect which pointed to ff9fb72bc077
> > > ("debugfs: return error values, not NULL") because the error checking is
> > > no longer correct in this driver.
> > > 
> > > Based on https://patchwork.kernel.org/patch/10865839/, it looks like
> > > this is supposed to go in for 5.2 but this needs to go in now as
> > > the error checking is currently broken without it. Can this get queued
> > > for Linus so we can get it in 5.0 stable?
> > 
> > That's odd, I can't see how the error checking is wrong here.  If the
> > directory is not created, an error will be returned, which should be
> > able to be handled by debugfs_create_file().
> > 
> > So with this patch does the error go away?
> > 
> 
> The full patch didn't apply cleanly and I didn't try to backport it
> for the reporter to test. I was going off of the theory that if the
> patch was there it would fix the problem.
> 
> What I _think_ is going wrong is dbgfs_dir is actually an errno value:
> 
> 
>         struct dentry *dbgfs_dir = vif->debugfs_dir;
>         struct iwl_mvm_vif *mvmvif = iwl_mvm_vif_from_mac80211(vif);
>         char buf[100];
> 
>         /*
>          * Check if debugfs directory already exist before creating it.
>          * This may happen when, for example, resetting hw or suspend-resume
>          */
>         if (!dbgfs_dir || mvmvif->dbgfs_dir)
>                 return;
> 
> 
> so this blows up in the snprintf
> 
>         snprintf(buf, 100, "../../../%pd3/%pd",
>                  dbgfs_dir,
>                  mvmvif->dbgfs_dir);

Ah, yeah, that's horrible.  They had the name before, why pull it out of
the dentry again?  That will blow up hard, but maybe printk should check
to see if the pointer really is a pointer first.

> Unless I misunderstood what the debugfs error change did. I think this
> also means the if check needs to look for IS_ERR and not just !dbgfs_dir.

Yes, that is correct.

thanks,

greg k-h

Re: [PATCH] iwlwifi: mvm: no need to check return value of debugfs_create functions

[Luca Coelho]

On Wed, 2019-03-27 at 10:53 +0900, Greg Kroah-Hartman wrote:
> On Tue, Mar 26, 2019 at 06:47:33PM -0700, Laura Abbott wrote:
> > On 3/26/19 6:26 PM, Greg Kroah-Hartman wrote:
> > > On Tue, Mar 26, 2019 at 04:55:54PM -0700, Laura Abbott wrote:
> > > > On 1/22/19 7:21 AM, Greg Kroah-Hartman wrote:
> > > > > diff --git a/drivers/net/wireless/intel/iwlwifi/mvm/debugfs-vif.c b/drivers/net/wireless/intel/iwlwifi/mvm/debugfs-vif.c
> > > > > index 33b0af24a537..c52cdc538678 100644
> > > > > --- a/drivers/net/wireless/intel/iwlwifi/mvm/debugfs-vif.c
> > > > > +++ b/drivers/net/wireless/intel/iwlwifi/mvm/debugfs-vif.c
> > > > > @@ -1446,9 +1446,8 @@ static ssize_t iwl_dbgfs_quota_min_read(struct file *file,
> > > > >    #define MVM_DEBUGFS_READ_WRITE_FILE_OPS(name, bufsz) \
> > > > >    	_MVM_DEBUGFS_READ_WRITE_FILE_OPS(name, bufsz, struct ieee80211_vif)
> > > > >    #define MVM_DEBUGFS_ADD_FILE_VIF(name, parent, mode) do {		\
> > > > > -		if (!debugfs_create_file(#name, mode, parent, vif,	\
> > > > > -					 &iwl_dbgfs_##name##_ops))	\
> > > > > -			goto err;					\
> > > > > +		debugfs_create_file(#name, mode, parent, vif,		\
> > > > > +				    &iwl_dbgfs_##name##_ops);		\
> > > > >    	} while (0)
> > > > >    MVM_DEBUGFS_READ_FILE_OPS(mac_params);
> > > > > @@ -1483,12 +1482,6 @@ void iwl_mvm_vif_dbgfs_register(struct iwl_mvm *mvm, struct ieee80211_vif *vif)
> > > > >    	mvmvif->dbgfs_dir = debugfs_create_dir("iwlmvm", dbgfs_dir);
> > > > > -	if (!mvmvif->dbgfs_dir) {
> > > > > -		IWL_ERR(mvm, "Failed to create debugfs directory under %pd\n",
> > > > > -			dbgfs_dir);
> > > > > -		return;
> > > > > -	}
> > > > > -
> > > > >    	if (iwlmvm_mod_params.power_scheme != IWL_POWER_SCHEME_CAM &&
> > > > >    	    ((vif->type == NL80211_IFTYPE_STATION && !vif->p2p) ||
> > > > >    	     (vif->type == NL80211_IFTYPE_STATION && vif->p2p)))
> > > > > @@ -1537,12 +1530,6 @@ void iwl_mvm_vif_dbgfs_register(struct iwl_mvm *mvm, struct ieee80211_vif *vif)
> > > > >    	mvmvif->dbgfs_slink = debugfs_create_symlink(dbgfs_dir->d_name.name,
> > > > >    						     mvm->debugfs_dir, buf);
> > > > > -	if (!mvmvif->dbgfs_slink)
> > > > > -		IWL_ERR(mvm, "Can't create debugfs symbolic link under %pd\n",
> > > > > -			dbgfs_dir);
> > > > > -	return;
> > > > > -err:
> > > > > -	IWL_ERR(mvm, "Can't create debugfs entity\n");
> > > > >    }
> > > > 
> > > > Fedora got a bug report https://bugzilla.redhat.com/show_bug.cgi?id=1691034
> > > > of a crash with 5.0 and the user did a bisect which pointed to ff9fb72bc077
> > > > ("debugfs: return error values, not NULL") because the error checking is
> > > > no longer correct in this driver.
> > > > 
> > > > Based on https://patchwork.kernel.org/patch/10865839/, it looks like
> > > > this is supposed to go in for 5.2 but this needs to go in now as
> > > > the error checking is currently broken without it. Can this get queued
> > > > for Linus so we can get it in 5.0 stable?
> > > 
> > > That's odd, I can't see how the error checking is wrong here.  If the
> > > directory is not created, an error will be returned, which should be
> > > able to be handled by debugfs_create_file().
> > > 
> > > So with this patch does the error go away?
> > > 
> > 
> > The full patch didn't apply cleanly and I didn't try to backport it
> > for the reporter to test. I was going off of the theory that if the
> > patch was there it would fix the problem.
> > 
> > What I _think_ is going wrong is dbgfs_dir is actually an errno value:
> > 
> > 
> >         struct dentry *dbgfs_dir = vif->debugfs_dir;
> >         struct iwl_mvm_vif *mvmvif = iwl_mvm_vif_from_mac80211(vif);
> >         char buf[100];
> > 
> >         /*
> >          * Check if debugfs directory already exist before creating it.
> >          * This may happen when, for example, resetting hw or suspend-resume
> >          */
> >         if (!dbgfs_dir || mvmvif->dbgfs_dir)
> >                 return;
> > 
> > 
> > so this blows up in the snprintf
> > 
> >         snprintf(buf, 100, "../../../%pd3/%pd",
> >                  dbgfs_dir,
> >                  mvmvif->dbgfs_dir);
> 
> Ah, yeah, that's horrible.  They had the name before, why pull it out of
> the dentry again?  That will blow up hard, but maybe printk should check
> to see if the pointer really is a pointer first.

I agree this is ugly.  But do you mean we could use
("../../../%pd3/%s", dbgfs_dir, "iwlmvm")? Or how did we have the name?

Also, this would solve the sprintf() problem, but still wouldn't solve
the real issue, which is not check for ERR in dbgfs_dir.


> > Unless I misunderstood what the debugfs error change did. I think this
> > also means the if check needs to look for IS_ERR and not just !dbgfs_dir.
> 
> Yes, that is correct.

Yeah, we can do that.  So this patch doesn't need to be sent for
v5.1-rc* and v5.0, right? At least I don't see how it would fix the
issue.  What we need is a new patch with the IS_ERR check.

--
Cheers,
Luca.

Re: [PATCH] iwlwifi: mvm: no need to check return value of debugfs_create functions

[Greg Kroah-Hartman]

On Wed, Mar 27, 2019 at 08:35:37AM +0200, Luca Coelho wrote:
> On Wed, 2019-03-27 at 10:53 +0900, Greg Kroah-Hartman wrote:
> > On Tue, Mar 26, 2019 at 06:47:33PM -0700, Laura Abbott wrote:
> > > On 3/26/19 6:26 PM, Greg Kroah-Hartman wrote:
> > > > On Tue, Mar 26, 2019 at 04:55:54PM -0700, Laura Abbott wrote:
> > > > > On 1/22/19 7:21 AM, Greg Kroah-Hartman wrote:
> > > > > > diff --git a/drivers/net/wireless/intel/iwlwifi/mvm/debugfs-vif.c b/drivers/net/wireless/intel/iwlwifi/mvm/debugfs-vif.c
> > > > > > index 33b0af24a537..c52cdc538678 100644
> > > > > > --- a/drivers/net/wireless/intel/iwlwifi/mvm/debugfs-vif.c
> > > > > > +++ b/drivers/net/wireless/intel/iwlwifi/mvm/debugfs-vif.c
> > > > > > @@ -1446,9 +1446,8 @@ static ssize_t iwl_dbgfs_quota_min_read(struct file *file,
> > > > > >    #define MVM_DEBUGFS_READ_WRITE_FILE_OPS(name, bufsz) \
> > > > > >    	_MVM_DEBUGFS_READ_WRITE_FILE_OPS(name, bufsz, struct ieee80211_vif)
> > > > > >    #define MVM_DEBUGFS_ADD_FILE_VIF(name, parent, mode) do {		\
> > > > > > -		if (!debugfs_create_file(#name, mode, parent, vif,	\
> > > > > > -					 &iwl_dbgfs_##name##_ops))	\
> > > > > > -			goto err;					\
> > > > > > +		debugfs_create_file(#name, mode, parent, vif,		\
> > > > > > +				    &iwl_dbgfs_##name##_ops);		\
> > > > > >    	} while (0)
> > > > > >    MVM_DEBUGFS_READ_FILE_OPS(mac_params);
> > > > > > @@ -1483,12 +1482,6 @@ void iwl_mvm_vif_dbgfs_register(struct iwl_mvm *mvm, struct ieee80211_vif *vif)
> > > > > >    	mvmvif->dbgfs_dir = debugfs_create_dir("iwlmvm", dbgfs_dir);
> > > > > > -	if (!mvmvif->dbgfs_dir) {
> > > > > > -		IWL_ERR(mvm, "Failed to create debugfs directory under %pd\n",
> > > > > > -			dbgfs_dir);
> > > > > > -		return;
> > > > > > -	}
> > > > > > -
> > > > > >    	if (iwlmvm_mod_params.power_scheme != IWL_POWER_SCHEME_CAM &&
> > > > > >    	    ((vif->type == NL80211_IFTYPE_STATION && !vif->p2p) ||
> > > > > >    	     (vif->type == NL80211_IFTYPE_STATION && vif->p2p)))
> > > > > > @@ -1537,12 +1530,6 @@ void iwl_mvm_vif_dbgfs_register(struct iwl_mvm *mvm, struct ieee80211_vif *vif)
> > > > > >    	mvmvif->dbgfs_slink = debugfs_create_symlink(dbgfs_dir->d_name.name,
> > > > > >    						     mvm->debugfs_dir, buf);
> > > > > > -	if (!mvmvif->dbgfs_slink)
> > > > > > -		IWL_ERR(mvm, "Can't create debugfs symbolic link under %pd\n",
> > > > > > -			dbgfs_dir);
> > > > > > -	return;
> > > > > > -err:
> > > > > > -	IWL_ERR(mvm, "Can't create debugfs entity\n");
> > > > > >    }
> > > > > 
> > > > > Fedora got a bug report https://bugzilla.redhat.com/show_bug.cgi?id=1691034
> > > > > of a crash with 5.0 and the user did a bisect which pointed to ff9fb72bc077
> > > > > ("debugfs: return error values, not NULL") because the error checking is
> > > > > no longer correct in this driver.
> > > > > 
> > > > > Based on https://patchwork.kernel.org/patch/10865839/, it looks like
> > > > > this is supposed to go in for 5.2 but this needs to go in now as
> > > > > the error checking is currently broken without it. Can this get queued
> > > > > for Linus so we can get it in 5.0 stable?
> > > > 
> > > > That's odd, I can't see how the error checking is wrong here.  If the
> > > > directory is not created, an error will be returned, which should be
> > > > able to be handled by debugfs_create_file().
> > > > 
> > > > So with this patch does the error go away?
> > > > 
> > > 
> > > The full patch didn't apply cleanly and I didn't try to backport it
> > > for the reporter to test. I was going off of the theory that if the
> > > patch was there it would fix the problem.
> > > 
> > > What I _think_ is going wrong is dbgfs_dir is actually an errno value:
> > > 
> > > 
> > >         struct dentry *dbgfs_dir = vif->debugfs_dir;
> > >         struct iwl_mvm_vif *mvmvif = iwl_mvm_vif_from_mac80211(vif);
> > >         char buf[100];
> > > 
> > >         /*
> > >          * Check if debugfs directory already exist before creating it.
> > >          * This may happen when, for example, resetting hw or suspend-resume
> > >          */
> > >         if (!dbgfs_dir || mvmvif->dbgfs_dir)
> > >                 return;
> > > 
> > > 
> > > so this blows up in the snprintf
> > > 
> > >         snprintf(buf, 100, "../../../%pd3/%pd",
> > >                  dbgfs_dir,
> > >                  mvmvif->dbgfs_dir);
> > 
> > Ah, yeah, that's horrible.  They had the name before, why pull it out of
> > the dentry again?  That will blow up hard, but maybe printk should check
> > to see if the pointer really is a pointer first.
> 
> I agree this is ugly.  But do you mean we could use
> ("../../../%pd3/%s", dbgfs_dir, "iwlmvm")? Or how did we have the name?

You "had" the name because you created this directory and name
previously :)

> Also, this would solve the sprintf() problem, but still wouldn't solve
> the real issue, which is not check for ERR in dbgfs_dir.

True.

> > > Unless I misunderstood what the debugfs error change did. I think this
> > > also means the if check needs to look for IS_ERR and not just !dbgfs_dir.
> > 
> > Yes, that is correct.
> 
> Yeah, we can do that.  So this patch doesn't need to be sent for
> v5.1-rc* and v5.0, right? At least I don't see how it would fix the
> issue.  What we need is a new patch with the IS_ERR check.

Ok, let me go create that right now...

thanks,

greg k-h

[PATCH] iwlwifi: properly check debugfs dentry before using it

[Greg Kroah-Hartman]

debugfs can now report an error code if something went wrong instead of
just NULL.  So if the return value is to be used as a "real" dentry, it
needs to be checked if it is an error before dereferencing it.

This is now happening because of ff9fb72bc077 ("debugfs: return error
values, not NULL").  If multiple iwlwifi devices are in the system, this
can cause problems when the driver attempts to create the main debugfs
directory again.  Later on in the code we fail horribly by trying to
dereference a pointer that is an error value.

Reported-by: Laura Abbott <labbott@redhat.com>
Cc: Johannes Berg <johannes.berg@intel.com>
Cc: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Cc: Luca Coelho <luciano.coelho@intel.com>
Cc: Intel Linux Wireless <linuxwifi@intel.com>
Cc: Kalle Valo <kvalo@codeaurora.org>
Cc: stable <stable@vger.kernel.org> # 5.0
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>


diff --git a/drivers/net/wireless/intel/iwlwifi/mvm/debugfs-vif.c b/drivers/net/wireless/intel/iwlwifi/mvm/debugfs-vif.c
index 2453ceabf00d..6925527d8457 100644
--- a/drivers/net/wireless/intel/iwlwifi/mvm/debugfs-vif.c
+++ b/drivers/net/wireless/intel/iwlwifi/mvm/debugfs-vif.c
@@ -774,8 +774,7 @@ void iwl_mvm_vif_dbgfs_register(struct iwl_mvm *mvm, struct ieee80211_vif *vif)
 		return;
 
 	mvmvif->dbgfs_dir = debugfs_create_dir("iwlmvm", dbgfs_dir);
-
-	if (!mvmvif->dbgfs_dir) {
+	if (IS_ERR_OR_NULL(mvmvif->dbgfs_dir)) {
 		IWL_ERR(mvm, "Failed to create debugfs directory under %pd\n",
 			dbgfs_dir);
 		return;

Re: [PATCH] iwlwifi: properly check debugfs dentry before using it

[Laura Abbott]

On 3/30/19 2:31 AM, Greg Kroah-Hartman wrote:
> debugfs can now report an error code if something went wrong instead of
> just NULL.  So if the return value is to be used as a "real" dentry, it
> needs to be checked if it is an error before dereferencing it.
> 
> This is now happening because of ff9fb72bc077 ("debugfs: return error
> values, not NULL").  If multiple iwlwifi devices are in the system, this
> can cause problems when the driver attempts to create the main debugfs
> directory again.  Later on in the code we fail horribly by trying to
> dereference a pointer that is an error value.
> 
> Reported-by: Laura Abbott <labbott@redhat.com>

Can you add

Reported-by:  Gabriel Ramirez <gabriello.ramirez@gmail.com>

for the bugzilla reporter who took the time to do the bisect?
I'll ask for testing as well.

> Cc: Johannes Berg <johannes.berg@intel.com>
> Cc: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
> Cc: Luca Coelho <luciano.coelho@intel.com>
> Cc: Intel Linux Wireless <linuxwifi@intel.com>
> Cc: Kalle Valo <kvalo@codeaurora.org>
> Cc: stable <stable@vger.kernel.org> # 5.0
> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> 
> 
> diff --git a/drivers/net/wireless/intel/iwlwifi/mvm/debugfs-vif.c b/drivers/net/wireless/intel/iwlwifi/mvm/debugfs-vif.c
> index 2453ceabf00d..6925527d8457 100644
> --- a/drivers/net/wireless/intel/iwlwifi/mvm/debugfs-vif.c
> +++ b/drivers/net/wireless/intel/iwlwifi/mvm/debugfs-vif.c
> @@ -774,8 +774,7 @@ void iwl_mvm_vif_dbgfs_register(struct iwl_mvm *mvm, struct ieee80211_vif *vif)
>   		return;
>   
>   	mvmvif->dbgfs_dir = debugfs_create_dir("iwlmvm", dbgfs_dir);
> -
> -	if (!mvmvif->dbgfs_dir) {
> +	if (IS_ERR_OR_NULL(mvmvif->dbgfs_dir)) {
>   		IWL_ERR(mvm, "Failed to create debugfs directory under %pd\n",
>   			dbgfs_dir);
>   		return;
> 

Re: [PATCH] iwlwifi: properly check debugfs dentry before using it

[Luca Coelho]

On Sat, 2019-03-30 at 10:31 +0100, Greg Kroah-Hartman wrote:
> debugfs can now report an error code if something went wrong instead
> of
> just NULL.  So if the return value is to be used as a "real" dentry,
> it
> needs to be checked if it is an error before dereferencing it.
> 
> This is now happening because of ff9fb72bc077 ("debugfs: return error
> values, not NULL").  If multiple iwlwifi devices are in the system,
> this
> can cause problems when the driver attempts to create the main
> debugfs
> directory again.  Later on in the code we fail horribly by trying to
> dereference a pointer that is an error value.
> 
> Reported-by: Laura Abbott <labbott@redhat.com>
> Cc: Johannes Berg <johannes.berg@intel.com>
> Cc: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
> Cc: Luca Coelho <luciano.coelho@intel.com>
> Cc: Intel Linux Wireless <linuxwifi@intel.com>
> Cc: Kalle Valo <kvalo@codeaurora.org>
> Cc: stable <stable@vger.kernel.org> # 5.0
> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> 
> 
> diff --git a/drivers/net/wireless/intel/iwlwifi/mvm/debugfs-vif.c
> b/drivers/net/wireless/intel/iwlwifi/mvm/debugfs-vif.c
> index 2453ceabf00d..6925527d8457 100644
> --- a/drivers/net/wireless/intel/iwlwifi/mvm/debugfs-vif.c
> +++ b/drivers/net/wireless/intel/iwlwifi/mvm/debugfs-vif.c
> @@ -774,8 +774,7 @@ void iwl_mvm_vif_dbgfs_register(struct iwl_mvm
> *mvm, struct ieee80211_vif *vif)
>  		return;
>  
>  	mvmvif->dbgfs_dir = debugfs_create_dir("iwlmvm", dbgfs_dir);
> -
> -	if (!mvmvif->dbgfs_dir) {
> +	if (IS_ERR_OR_NULL(mvmvif->dbgfs_dir)) {
>  		IWL_ERR(mvm, "Failed to create debugfs directory under
> %pd\n",
>  			dbgfs_dir);
>  		return;

Thanks! I've applied this internally and will send upstream for v5.1-
rc* following our normal upstreaming process.

I added the other Reported-by that Laura asked for and added "mvm:" to
the subject.

--
Cheers,
Luca.