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authorJakub Kicinski <kuba@kernel.org>2023-11-29 19:43:34 -0800
committerJakub Kicinski <kuba@kernel.org>2023-11-29 19:43:34 -0800
commit300fbb247eb3d2146b37c8dc127056f695091218 (patch)
tree833813d22c7ac4f68f52f3dc11ac561453a95fdb /fs
parent0d47fa5cc91b9c8a0c90833bf1705048b2295714 (diff)
parent4ded3bfe1db655367642aadba91aee770cbab317 (diff)
Merge tag 'wireless-2023-11-29' of git://git.kernel.org/pub/scm/linux/kernel/git/wireless/wireless
Johannes Berg says: ==================== wireless fixes: - debugfs had a deadlock (removal vs. use of files), fixes going through wireless ACKed by Greg - support for HT STAs on 320 MHz channels, even if it's not clear that should ever happen (that's 6 GHz), best not to WARN() - fix for the previous CQM fix that broke most cases - various wiphy locking fixes - various small driver fixes * tag 'wireless-2023-11-29' of git://git.kernel.org/pub/scm/linux/kernel/git/wireless/wireless: wifi: mac80211: use wiphy locked debugfs for sdata/link wifi: mac80211: use wiphy locked debugfs helpers for agg_status wifi: cfg80211: add locked debugfs wrappers debugfs: add API to allow debugfs operations cancellation debugfs: annotate debugfs handlers vs. removal with lockdep debugfs: fix automount d_fsdata usage wifi: mac80211: handle 320 MHz in ieee80211_ht_cap_ie_to_sta_ht_cap wifi: avoid offset calculation on NULL pointer wifi: cfg80211: hold wiphy mutex for send_interface wifi: cfg80211: lock wiphy mutex for rfkill poll wifi: cfg80211: fix CQM for non-range use wifi: mac80211: do not pass AP_VLAN vif pointer to drivers during flush wifi: iwlwifi: mvm: fix an error code in iwl_mvm_mld_add_sta() wifi: mt76: mt7925: fix typo in mt7925_init_he_caps wifi: mt76: mt7921: fix 6GHz disabled by the missing default CLC config ==================== Link: https://lore.kernel.org/r/20231129150809.31083-3-johannes@sipsolutions.net Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Diffstat (limited to 'fs')
-rw-r--r--fs/debugfs/file.c100
-rw-r--r--fs/debugfs/inode.c71
-rw-r--r--fs/debugfs/internal.h21
3 files changed, 182 insertions, 10 deletions
diff --git a/fs/debugfs/file.c b/fs/debugfs/file.c
index c45e8c2d62e1..a5ade8c16375 100644
--- a/fs/debugfs/file.c
+++ b/fs/debugfs/file.c
@@ -84,6 +84,14 @@ int debugfs_file_get(struct dentry *dentry)
struct debugfs_fsdata *fsd;
void *d_fsd;
+ /*
+ * This could only happen if some debugfs user erroneously calls
+ * debugfs_file_get() on a dentry that isn't even a file, let
+ * them know about it.
+ */
+ if (WARN_ON(!d_is_reg(dentry)))
+ return -EINVAL;
+
d_fsd = READ_ONCE(dentry->d_fsdata);
if (!((unsigned long)d_fsd & DEBUGFS_FSDATA_IS_REAL_FOPS_BIT)) {
fsd = d_fsd;
@@ -100,6 +108,14 @@ int debugfs_file_get(struct dentry *dentry)
kfree(fsd);
fsd = READ_ONCE(dentry->d_fsdata);
}
+#ifdef CONFIG_LOCKDEP
+ fsd->lock_name = kasprintf(GFP_KERNEL, "debugfs:%pd", dentry);
+ lockdep_register_key(&fsd->key);
+ lockdep_init_map(&fsd->lockdep_map, fsd->lock_name ?: "debugfs",
+ &fsd->key, 0);
+#endif
+ INIT_LIST_HEAD(&fsd->cancellations);
+ mutex_init(&fsd->cancellations_mtx);
}
/*
@@ -116,6 +132,8 @@ int debugfs_file_get(struct dentry *dentry)
if (!refcount_inc_not_zero(&fsd->active_users))
return -EIO;
+ lock_map_acquire_read(&fsd->lockdep_map);
+
return 0;
}
EXPORT_SYMBOL_GPL(debugfs_file_get);
@@ -133,11 +151,93 @@ void debugfs_file_put(struct dentry *dentry)
{
struct debugfs_fsdata *fsd = READ_ONCE(dentry->d_fsdata);
+ lock_map_release(&fsd->lockdep_map);
+
if (refcount_dec_and_test(&fsd->active_users))
complete(&fsd->active_users_drained);
}
EXPORT_SYMBOL_GPL(debugfs_file_put);
+/**
+ * debugfs_enter_cancellation - enter a debugfs cancellation
+ * @file: the file being accessed
+ * @cancellation: the cancellation object, the cancel callback
+ * inside of it must be initialized
+ *
+ * When a debugfs file is removed it needs to wait for all active
+ * operations to complete. However, the operation itself may need
+ * to wait for hardware or completion of some asynchronous process
+ * or similar. As such, it may need to be cancelled to avoid long
+ * waits or even deadlocks.
+ *
+ * This function can be used inside a debugfs handler that may
+ * need to be cancelled. As soon as this function is called, the
+ * cancellation's 'cancel' callback may be called, at which point
+ * the caller should proceed to call debugfs_leave_cancellation()
+ * and leave the debugfs handler function as soon as possible.
+ * Note that the 'cancel' callback is only ever called in the
+ * context of some kind of debugfs_remove().
+ *
+ * This function must be paired with debugfs_leave_cancellation().
+ */
+void debugfs_enter_cancellation(struct file *file,
+ struct debugfs_cancellation *cancellation)
+{
+ struct debugfs_fsdata *fsd;
+ struct dentry *dentry = F_DENTRY(file);
+
+ INIT_LIST_HEAD(&cancellation->list);
+
+ if (WARN_ON(!d_is_reg(dentry)))
+ return;
+
+ if (WARN_ON(!cancellation->cancel))
+ return;
+
+ fsd = READ_ONCE(dentry->d_fsdata);
+ if (WARN_ON(!fsd ||
+ ((unsigned long)fsd & DEBUGFS_FSDATA_IS_REAL_FOPS_BIT)))
+ return;
+
+ mutex_lock(&fsd->cancellations_mtx);
+ list_add(&cancellation->list, &fsd->cancellations);
+ mutex_unlock(&fsd->cancellations_mtx);
+
+ /* if we're already removing wake it up to cancel */
+ if (d_unlinked(dentry))
+ complete(&fsd->active_users_drained);
+}
+EXPORT_SYMBOL_GPL(debugfs_enter_cancellation);
+
+/**
+ * debugfs_leave_cancellation - leave cancellation section
+ * @file: the file being accessed
+ * @cancellation: the cancellation previously registered with
+ * debugfs_enter_cancellation()
+ *
+ * See the documentation of debugfs_enter_cancellation().
+ */
+void debugfs_leave_cancellation(struct file *file,
+ struct debugfs_cancellation *cancellation)
+{
+ struct debugfs_fsdata *fsd;
+ struct dentry *dentry = F_DENTRY(file);
+
+ if (WARN_ON(!d_is_reg(dentry)))
+ return;
+
+ fsd = READ_ONCE(dentry->d_fsdata);
+ if (WARN_ON(!fsd ||
+ ((unsigned long)fsd & DEBUGFS_FSDATA_IS_REAL_FOPS_BIT)))
+ return;
+
+ mutex_lock(&fsd->cancellations_mtx);
+ if (!list_empty(&cancellation->list))
+ list_del(&cancellation->list);
+ mutex_unlock(&fsd->cancellations_mtx);
+}
+EXPORT_SYMBOL_GPL(debugfs_leave_cancellation);
+
/*
* Only permit access to world-readable files when the kernel is locked down.
* We also need to exclude any file that has ways to write or alter it as root
diff --git a/fs/debugfs/inode.c b/fs/debugfs/inode.c
index 5d41765e0c77..e4e7fe1bd9fb 100644
--- a/fs/debugfs/inode.c
+++ b/fs/debugfs/inode.c
@@ -236,17 +236,29 @@ static const struct super_operations debugfs_super_operations = {
static void debugfs_release_dentry(struct dentry *dentry)
{
- void *fsd = dentry->d_fsdata;
+ struct debugfs_fsdata *fsd = dentry->d_fsdata;
- if (!((unsigned long)fsd & DEBUGFS_FSDATA_IS_REAL_FOPS_BIT))
- kfree(dentry->d_fsdata);
+ if ((unsigned long)fsd & DEBUGFS_FSDATA_IS_REAL_FOPS_BIT)
+ return;
+
+ /* check it wasn't a dir (no fsdata) or automount (no real_fops) */
+ if (fsd && fsd->real_fops) {
+#ifdef CONFIG_LOCKDEP
+ lockdep_unregister_key(&fsd->key);
+ kfree(fsd->lock_name);
+#endif
+ WARN_ON(!list_empty(&fsd->cancellations));
+ mutex_destroy(&fsd->cancellations_mtx);
+ }
+
+ kfree(fsd);
}
static struct vfsmount *debugfs_automount(struct path *path)
{
- debugfs_automount_t f;
- f = (debugfs_automount_t)path->dentry->d_fsdata;
- return f(path->dentry, d_inode(path->dentry)->i_private);
+ struct debugfs_fsdata *fsd = path->dentry->d_fsdata;
+
+ return fsd->automount(path->dentry, d_inode(path->dentry)->i_private);
}
static const struct dentry_operations debugfs_dops = {
@@ -634,13 +646,23 @@ struct dentry *debugfs_create_automount(const char *name,
void *data)
{
struct dentry *dentry = start_creating(name, parent);
+ struct debugfs_fsdata *fsd;
struct inode *inode;
if (IS_ERR(dentry))
return dentry;
+ fsd = kzalloc(sizeof(*fsd), GFP_KERNEL);
+ if (!fsd) {
+ failed_creating(dentry);
+ return ERR_PTR(-ENOMEM);
+ }
+
+ fsd->automount = f;
+
if (!(debugfs_allow & DEBUGFS_ALLOW_API)) {
failed_creating(dentry);
+ kfree(fsd);
return ERR_PTR(-EPERM);
}
@@ -648,13 +670,14 @@ struct dentry *debugfs_create_automount(const char *name,
if (unlikely(!inode)) {
pr_err("out of free dentries, can not create automount '%s'\n",
name);
+ kfree(fsd);
return failed_creating(dentry);
}
make_empty_dir_inode(inode);
inode->i_flags |= S_AUTOMOUNT;
inode->i_private = data;
- dentry->d_fsdata = (void *)f;
+ dentry->d_fsdata = fsd;
/* directory inodes start off with i_nlink == 2 (for "." entry) */
inc_nlink(inode);
d_instantiate(dentry, inode);
@@ -731,8 +754,40 @@ static void __debugfs_file_removed(struct dentry *dentry)
fsd = READ_ONCE(dentry->d_fsdata);
if ((unsigned long)fsd & DEBUGFS_FSDATA_IS_REAL_FOPS_BIT)
return;
- if (!refcount_dec_and_test(&fsd->active_users))
+
+ lock_map_acquire(&fsd->lockdep_map);
+ lock_map_release(&fsd->lockdep_map);
+
+ /* if we hit zero, just wait for all to finish */
+ if (!refcount_dec_and_test(&fsd->active_users)) {
+ wait_for_completion(&fsd->active_users_drained);
+ return;
+ }
+
+ /* if we didn't hit zero, try to cancel any we can */
+ while (refcount_read(&fsd->active_users)) {
+ struct debugfs_cancellation *c;
+
+ /*
+ * Lock the cancellations. Note that the cancellations
+ * structs are meant to be on the stack, so we need to
+ * ensure we either use them here or don't touch them,
+ * and debugfs_leave_cancellation() will wait for this
+ * to be finished processing before exiting one. It may
+ * of course win and remove the cancellation, but then
+ * chances are we never even got into this bit, we only
+ * do if the refcount isn't zero already.
+ */
+ mutex_lock(&fsd->cancellations_mtx);
+ while ((c = list_first_entry_or_null(&fsd->cancellations,
+ typeof(*c), list))) {
+ list_del_init(&c->list);
+ c->cancel(dentry, c->cancel_data);
+ }
+ mutex_unlock(&fsd->cancellations_mtx);
+
wait_for_completion(&fsd->active_users_drained);
+ }
}
static void remove_one(struct dentry *victim)
diff --git a/fs/debugfs/internal.h b/fs/debugfs/internal.h
index 92af8ae31313..0c4c68cf161f 100644
--- a/fs/debugfs/internal.h
+++ b/fs/debugfs/internal.h
@@ -7,6 +7,8 @@
#ifndef _DEBUGFS_INTERNAL_H_
#define _DEBUGFS_INTERNAL_H_
+#include <linux/lockdep.h>
+#include <linux/list.h>
struct file_operations;
@@ -17,8 +19,23 @@ extern const struct file_operations debugfs_full_proxy_file_operations;
struct debugfs_fsdata {
const struct file_operations *real_fops;
- refcount_t active_users;
- struct completion active_users_drained;
+ union {
+ /* automount_fn is used when real_fops is NULL */
+ debugfs_automount_t automount;
+ struct {
+ refcount_t active_users;
+ struct completion active_users_drained;
+#ifdef CONFIG_LOCKDEP
+ struct lockdep_map lockdep_map;
+ struct lock_class_key key;
+ char *lock_name;
+#endif
+
+ /* protect cancellations */
+ struct mutex cancellations_mtx;
+ struct list_head cancellations;
+ };
+ };
};
/*