diff options
Diffstat (limited to 'fs/debugfs')
| -rw-r--r-- | fs/debugfs/file.c | 436 | ||||
| -rw-r--r-- | fs/debugfs/inode.c | 108 | ||||
| -rw-r--r-- | fs/debugfs/internal.h | 26 |
3 files changed, 484 insertions, 86 deletions
diff --git a/fs/debugfs/file.c b/fs/debugfs/file.c index d2ba12e23ed9..9c1c9a01b7e5 100644 --- a/fs/debugfs/file.c +++ b/fs/debugfs/file.c @@ -22,6 +22,12 @@ #include <linux/slab.h> #include <linux/atomic.h> #include <linux/device.h> +#include <linux/srcu.h> +#include <asm/poll.h> + +#include "internal.h" + +struct poll_table_struct; static ssize_t default_read_file(struct file *file, char __user *buf, size_t count, loff_t *ppos) @@ -35,27 +41,293 @@ static ssize_t default_write_file(struct file *file, const char __user *buf, return count; } -const struct file_operations debugfs_file_operations = { +const struct file_operations debugfs_noop_file_operations = { .read = default_read_file, .write = default_write_file, .open = simple_open, .llseek = noop_llseek, }; -static struct dentry *debugfs_create_mode(const char *name, umode_t mode, - struct dentry *parent, void *value, - const struct file_operations *fops, - const struct file_operations *fops_ro, - const struct file_operations *fops_wo) +/** + * debugfs_use_file_start - mark the beginning of file data access + * @dentry: the dentry object whose data is being accessed. + * @srcu_idx: a pointer to some memory to store a SRCU index in. + * + * Up to a matching call to debugfs_use_file_finish(), any + * successive call into the file removing functions debugfs_remove() + * and debugfs_remove_recursive() will block. Since associated private + * file data may only get freed after a successful return of any of + * the removal functions, you may safely access it after a successful + * call to debugfs_use_file_start() without worrying about + * lifetime issues. + * + * If -%EIO is returned, the file has already been removed and thus, + * it is not safe to access any of its data. If, on the other hand, + * it is allowed to access the file data, zero is returned. + * + * Regardless of the return code, any call to + * debugfs_use_file_start() must be followed by a matching call + * to debugfs_use_file_finish(). + */ +int debugfs_use_file_start(const struct dentry *dentry, int *srcu_idx) + __acquires(&debugfs_srcu) +{ + *srcu_idx = srcu_read_lock(&debugfs_srcu); + barrier(); + if (d_unlinked(dentry)) + return -EIO; + return 0; +} +EXPORT_SYMBOL_GPL(debugfs_use_file_start); + +/** + * debugfs_use_file_finish - mark the end of file data access + * @srcu_idx: the SRCU index "created" by a former call to + * debugfs_use_file_start(). + * + * Allow any ongoing concurrent call into debugfs_remove() or + * debugfs_remove_recursive() blocked by a former call to + * debugfs_use_file_start() to proceed and return to its caller. + */ +void debugfs_use_file_finish(int srcu_idx) __releases(&debugfs_srcu) +{ + srcu_read_unlock(&debugfs_srcu, srcu_idx); +} +EXPORT_SYMBOL_GPL(debugfs_use_file_finish); + +#define F_DENTRY(filp) ((filp)->f_path.dentry) + +#define REAL_FOPS_DEREF(dentry) \ + ((const struct file_operations *)(dentry)->d_fsdata) + +static int open_proxy_open(struct inode *inode, struct file *filp) +{ + const struct dentry *dentry = F_DENTRY(filp); + const struct file_operations *real_fops = NULL; + int srcu_idx, r; + + r = debugfs_use_file_start(dentry, &srcu_idx); + if (r) { + r = -ENOENT; + goto out; + } + + real_fops = REAL_FOPS_DEREF(dentry); + real_fops = fops_get(real_fops); + if (!real_fops) { + /* Huh? Module did not clean up after itself at exit? */ + WARN(1, "debugfs file owner did not clean up at exit: %pd", + dentry); + r = -ENXIO; + goto out; + } + replace_fops(filp, real_fops); + + if (real_fops->open) + r = real_fops->open(inode, filp); + +out: + fops_put(real_fops); + debugfs_use_file_finish(srcu_idx); + return r; +} + +const struct file_operations debugfs_open_proxy_file_operations = { + .open = open_proxy_open, +}; + +#define PROTO(args...) args +#define ARGS(args...) args + +#define FULL_PROXY_FUNC(name, ret_type, filp, proto, args) \ +static ret_type full_proxy_ ## name(proto) \ +{ \ + const struct dentry *dentry = F_DENTRY(filp); \ + const struct file_operations *real_fops = \ + REAL_FOPS_DEREF(dentry); \ + int srcu_idx; \ + ret_type r; \ + \ + r = debugfs_use_file_start(dentry, &srcu_idx); \ + if (likely(!r)) \ + r = real_fops->name(args); \ + debugfs_use_file_finish(srcu_idx); \ + return r; \ +} + +FULL_PROXY_FUNC(llseek, loff_t, filp, + PROTO(struct file *filp, loff_t offset, int whence), + ARGS(filp, offset, whence)); + +FULL_PROXY_FUNC(read, ssize_t, filp, + PROTO(struct file *filp, char __user *buf, size_t size, + loff_t *ppos), + ARGS(filp, buf, size, ppos)); + +FULL_PROXY_FUNC(write, ssize_t, filp, + PROTO(struct file *filp, const char __user *buf, size_t size, + loff_t *ppos), + ARGS(filp, buf, size, ppos)); + +FULL_PROXY_FUNC(unlocked_ioctl, long, filp, + PROTO(struct file *filp, unsigned int cmd, unsigned long arg), + ARGS(filp, cmd, arg)); + +static unsigned int full_proxy_poll(struct file *filp, + struct poll_table_struct *wait) +{ + const struct dentry *dentry = F_DENTRY(filp); + const struct file_operations *real_fops = REAL_FOPS_DEREF(dentry); + int srcu_idx; + unsigned int r = 0; + + if (debugfs_use_file_start(dentry, &srcu_idx)) { + debugfs_use_file_finish(srcu_idx); + return POLLHUP; + } + + r = real_fops->poll(filp, wait); + debugfs_use_file_finish(srcu_idx); + return r; +} + +static int full_proxy_release(struct inode *inode, struct file *filp) +{ + const struct dentry *dentry = F_DENTRY(filp); + const struct file_operations *real_fops = REAL_FOPS_DEREF(dentry); + const struct file_operations *proxy_fops = filp->f_op; + int r = 0; + + /* + * We must not protect this against removal races here: the + * original releaser should be called unconditionally in order + * not to leak any resources. Releasers must not assume that + * ->i_private is still being meaningful here. + */ + if (real_fops->release) + r = real_fops->release(inode, filp); + + replace_fops(filp, d_inode(dentry)->i_fop); + kfree((void *)proxy_fops); + fops_put(real_fops); + return 0; +} + +static void __full_proxy_fops_init(struct file_operations *proxy_fops, + const struct file_operations *real_fops) +{ + proxy_fops->release = full_proxy_release; + if (real_fops->llseek) + proxy_fops->llseek = full_proxy_llseek; + if (real_fops->read) + proxy_fops->read = full_proxy_read; + if (real_fops->write) + proxy_fops->write = full_proxy_write; + if (real_fops->poll) + proxy_fops->poll = full_proxy_poll; + if (real_fops->unlocked_ioctl) + proxy_fops->unlocked_ioctl = full_proxy_unlocked_ioctl; +} + +static int full_proxy_open(struct inode *inode, struct file *filp) +{ + const struct dentry *dentry = F_DENTRY(filp); + const struct file_operations *real_fops = NULL; + struct file_operations *proxy_fops = NULL; + int srcu_idx, r; + + r = debugfs_use_file_start(dentry, &srcu_idx); + if (r) { + r = -ENOENT; + goto out; + } + + real_fops = REAL_FOPS_DEREF(dentry); + real_fops = fops_get(real_fops); + if (!real_fops) { + /* Huh? Module did not cleanup after itself at exit? */ + WARN(1, "debugfs file owner did not clean up at exit: %pd", + dentry); + r = -ENXIO; + goto out; + } + + proxy_fops = kzalloc(sizeof(*proxy_fops), GFP_KERNEL); + if (!proxy_fops) { + r = -ENOMEM; + goto free_proxy; + } + __full_proxy_fops_init(proxy_fops, real_fops); + replace_fops(filp, proxy_fops); + + if (real_fops->open) { + r = real_fops->open(inode, filp); + + if (filp->f_op != proxy_fops) { + /* No protection against file removal anymore. */ + WARN(1, "debugfs file owner replaced proxy fops: %pd", + dentry); + goto free_proxy; + } + } + + goto out; +free_proxy: + kfree(proxy_fops); + fops_put(real_fops); +out: + debugfs_use_file_finish(srcu_idx); + return r; +} + +const struct file_operations debugfs_full_proxy_file_operations = { + .open = full_proxy_open, +}; + +ssize_t debugfs_attr_read(struct file *file, char __user *buf, + size_t len, loff_t *ppos) +{ + ssize_t ret; + int srcu_idx; + + ret = debugfs_use_file_start(F_DENTRY(file), &srcu_idx); + if (likely(!ret)) + ret = simple_attr_read(file, buf, len, ppos); + debugfs_use_file_finish(srcu_idx); + return ret; +} +EXPORT_SYMBOL_GPL(debugfs_attr_read); + +ssize_t debugfs_attr_write(struct file *file, const char __user *buf, + size_t len, loff_t *ppos) +{ + ssize_t ret; + int srcu_idx; + + ret = debugfs_use_file_start(F_DENTRY(file), &srcu_idx); + if (likely(!ret)) + ret = simple_attr_write(file, buf, len, ppos); + debugfs_use_file_finish(srcu_idx); + return ret; +} +EXPORT_SYMBOL_GPL(debugfs_attr_write); + +static struct dentry *debugfs_create_mode_unsafe(const char *name, umode_t mode, + struct dentry *parent, void *value, + const struct file_operations *fops, + const struct file_operations *fops_ro, + const struct file_operations *fops_wo) { /* if there are no write bits set, make read only */ if (!(mode & S_IWUGO)) - return debugfs_create_file(name, mode, parent, value, fops_ro); + return debugfs_create_file_unsafe(name, mode, parent, value, + fops_ro); /* if there are no read bits set, make write only */ if (!(mode & S_IRUGO)) - return debugfs_create_file(name, mode, parent, value, fops_wo); + return debugfs_create_file_unsafe(name, mode, parent, value, + fops_wo); - return debugfs_create_file(name, mode, parent, value, fops); + return debugfs_create_file_unsafe(name, mode, parent, value, fops); } static int debugfs_u8_set(void *data, u64 val) @@ -68,9 +340,9 @@ static int debugfs_u8_get(void *data, u64 *val) *val = *(u8 *)data; return 0; } -DEFINE_SIMPLE_ATTRIBUTE(fops_u8, debugfs_u8_get, debugfs_u8_set, "%llu\n"); -DEFINE_SIMPLE_ATTRIBUTE(fops_u8_ro, debugfs_u8_get, NULL, "%llu\n"); -DEFINE_SIMPLE_ATTRIBUTE(fops_u8_wo, NULL, debugfs_u8_set, "%llu\n"); +DEFINE_DEBUGFS_ATTRIBUTE(fops_u8, debugfs_u8_get, debugfs_u8_set, "%llu\n"); +DEFINE_DEBUGFS_ATTRIBUTE(fops_u8_ro, debugfs_u8_get, NULL, "%llu\n"); +DEFINE_DEBUGFS_ATTRIBUTE(fops_u8_wo, NULL, debugfs_u8_set, "%llu\n"); /** * debugfs_create_u8 - create a debugfs file that is used to read and write an unsigned 8-bit value @@ -99,7 +371,7 @@ DEFINE_SIMPLE_ATTRIBUTE(fops_u8_wo, NULL, debugfs_u8_set, "%llu\n"); struct dentry *debugfs_create_u8(const char *name, umode_t mode, struct dentry *parent, u8 *value) { - return debugfs_create_mode(name, mode, parent, value, &fops_u8, + return debugfs_create_mode_unsafe(name, mode, parent, value, &fops_u8, &fops_u8_ro, &fops_u8_wo); } EXPORT_SYMBOL_GPL(debugfs_create_u8); @@ -114,9 +386,9 @@ static int debugfs_u16_get(void *data, u64 *val) *val = *(u16 *)data; return 0; } -DEFINE_SIMPLE_ATTRIBUTE(fops_u16, debugfs_u16_get, debugfs_u16_set, "%llu\n"); -DEFINE_SIMPLE_ATTRIBUTE(fops_u16_ro, debugfs_u16_get, NULL, "%llu\n"); -DEFINE_SIMPLE_ATTRIBUTE(fops_u16_wo, NULL, debugfs_u16_set, "%llu\n"); +DEFINE_DEBUGFS_ATTRIBUTE(fops_u16, debugfs_u16_get, debugfs_u16_set, "%llu\n"); +DEFINE_DEBUGFS_ATTRIBUTE(fops_u16_ro, debugfs_u16_get, NULL, "%llu\n"); +DEFINE_DEBUGFS_ATTRIBUTE(fops_u16_wo, NULL, debugfs_u16_set, "%llu\n"); /** * debugfs_create_u16 - create a debugfs file that is used to read and write an unsigned 16-bit value @@ -145,7 +417,7 @@ DEFINE_SIMPLE_ATTRIBUTE(fops_u16_wo, NULL, debugfs_u16_set, "%llu\n"); struct dentry *debugfs_create_u16(const char *name, umode_t mode, struct dentry *parent, u16 *value) { - return debugfs_create_mode(name, mode, parent, value, &fops_u16, + return debugfs_create_mode_unsafe(name, mode, parent, value, &fops_u16, &fops_u16_ro, &fops_u16_wo); } EXPORT_SYMBOL_GPL(debugfs_create_u16); @@ -160,9 +432,9 @@ static int debugfs_u32_get(void *data, u64 *val) *val = *(u32 *)data; return 0; } -DEFINE_SIMPLE_ATTRIBUTE(fops_u32, debugfs_u32_get, debugfs_u32_set, "%llu\n"); -DEFINE_SIMPLE_ATTRIBUTE(fops_u32_ro, debugfs_u32_get, NULL, "%llu\n"); -DEFINE_SIMPLE_ATTRIBUTE(fops_u32_wo, NULL, debugfs_u32_set, "%llu\n"); +DEFINE_DEBUGFS_ATTRIBUTE(fops_u32, debugfs_u32_get, debugfs_u32_set, "%llu\n"); +DEFINE_DEBUGFS_ATTRIBUTE(fops_u32_ro, debugfs_u32_get, NULL, "%llu\n"); +DEFINE_DEBUGFS_ATTRIBUTE(fops_u32_wo, NULL, debugfs_u32_set, "%llu\n"); /** * debugfs_create_u32 - create a debugfs file that is used to read and write an unsigned 32-bit value @@ -191,7 +463,7 @@ DEFINE_SIMPLE_ATTRIBUTE(fops_u32_wo, NULL, debugfs_u32_set, "%llu\n"); struct dentry *debugfs_create_u32(const char *name, umode_t mode, struct dentry *parent, u32 *value) { - return debugfs_create_mode(name, mode, parent, value, &fops_u32, + return debugfs_create_mode_unsafe(name, mode, parent, value, &fops_u32, &fops_u32_ro, &fops_u32_wo); } EXPORT_SYMBOL_GPL(debugfs_create_u32); @@ -207,9 +479,9 @@ static int debugfs_u64_get(void *data, u64 *val) *val = *(u64 *)data; return 0; } -DEFINE_SIMPLE_ATTRIBUTE(fops_u64, debugfs_u64_get, debugfs_u64_set, "%llu\n"); -DEFINE_SIMPLE_ATTRIBUTE(fops_u64_ro, debugfs_u64_get, NULL, "%llu\n"); -DEFINE_SIMPLE_ATTRIBUTE(fops_u64_wo, NULL, debugfs_u64_set, "%llu\n"); +DEFINE_DEBUGFS_ATTRIBUTE(fops_u64, debugfs_u64_get, debugfs_u64_set, "%llu\n"); +DEFINE_DEBUGFS_ATTRIBUTE(fops_u64_ro, debugfs_u64_get, NULL, "%llu\n"); +DEFINE_DEBUGFS_ATTRIBUTE(fops_u64_wo, NULL, debugfs_u64_set, "%llu\n"); /** * debugfs_create_u64 - create a debugfs file that is used to read and write an unsigned 64-bit value @@ -238,7 +510,7 @@ DEFINE_SIMPLE_ATTRIBUTE(fops_u64_wo, NULL, debugfs_u64_set, "%llu\n"); struct dentry *debugfs_create_u64(const char *name, umode_t mode, struct dentry *parent, u64 *value) { - return debugfs_create_mode(name, mode, parent, value, &fops_u64, + return debugfs_create_mode_unsafe(name, mode, parent, value, &fops_u64, &fops_u64_ro, &fops_u64_wo); } EXPORT_SYMBOL_GPL(debugfs_create_u64); @@ -254,9 +526,10 @@ static int debugfs_ulong_get(void *data, u64 *val) *val = *(unsigned long *)data; return 0; } -DEFINE_SIMPLE_ATTRIBUTE(fops_ulong, debugfs_ulong_get, debugfs_ulong_set, "%llu\n"); -DEFINE_SIMPLE_ATTRIBUTE(fops_ulong_ro, debugfs_ulong_get, NULL, "%llu\n"); -DEFINE_SIMPLE_ATTRIBUTE(fops_ulong_wo, NULL, debugfs_ulong_set, "%llu\n"); +DEFINE_DEBUGFS_ATTRIBUTE(fops_ulong, debugfs_ulong_get, debugfs_ulong_set, + "%llu\n"); +DEFINE_DEBUGFS_ATTRIBUTE(fops_ulong_ro, debugfs_ulong_get, NULL, "%llu\n"); +DEFINE_DEBUGFS_ATTRIBUTE(fops_ulong_wo, NULL, debugfs_ulong_set, "%llu\n"); /** * debugfs_create_ulong - create a debugfs file that is used to read and write @@ -286,26 +559,30 @@ DEFINE_SIMPLE_ATTRIBUTE(fops_ulong_wo, NULL, debugfs_ulong_set, "%llu\n"); struct dentry *debugfs_create_ulong(const char *name, umode_t mode, struct dentry *parent, unsigned long *value) { - return debugfs_create_mode(name, mode, parent, value, &fops_ulong, - &fops_ulong_ro, &fops_ulong_wo); + return debugfs_create_mode_unsafe(name, mode, parent, value, + &fops_ulong, &fops_ulong_ro, + &fops_ulong_wo); } EXPORT_SYMBOL_GPL(debugfs_create_ulong); -DEFINE_SIMPLE_ATTRIBUTE(fops_x8, debugfs_u8_get, debugfs_u8_set, "0x%02llx\n"); -DEFINE_SIMPLE_ATTRIBUTE(fops_x8_ro, debugfs_u8_get, NULL, "0x%02llx\n"); -DEFINE_SIMPLE_ATTRIBUTE(fops_x8_wo, NULL, debugfs_u8_set, "0x%02llx\n"); +DEFINE_DEBUGFS_ATTRIBUTE(fops_x8, debugfs_u8_get, debugfs_u8_set, "0x%02llx\n"); +DEFINE_DEBUGFS_ATTRIBUTE(fops_x8_ro, debugfs_u8_get, NULL, "0x%02llx\n"); +DEFINE_DEBUGFS_ATTRIBUTE(fops_x8_wo, NULL, debugfs_u8_set, "0x%02llx\n"); -DEFINE_SIMPLE_ATTRIBUTE(fops_x16, debugfs_u16_get, debugfs_u16_set, "0x%04llx\n"); -DEFINE_SIMPLE_ATTRIBUTE(fops_x16_ro, debugfs_u16_get, NULL, "0x%04llx\n"); -DEFINE_SIMPLE_ATTRIBUTE(fops_x16_wo, NULL, debugfs_u16_set, "0x%04llx\n"); +DEFINE_DEBUGFS_ATTRIBUTE(fops_x16, debugfs_u16_get, debugfs_u16_set, + "0x%04llx\n"); +DEFINE_DEBUGFS_ATTRIBUTE(fops_x16_ro, debugfs_u16_get, NULL, "0x%04llx\n"); +DEFINE_DEBUGFS_ATTRIBUTE(fops_x16_wo, NULL, debugfs_u16_set, "0x%04llx\n"); -DEFINE_SIMPLE_ATTRIBUTE(fops_x32, debugfs_u32_get, debugfs_u32_set, "0x%08llx\n"); -DEFINE_SIMPLE_ATTRIBUTE(fops_x32_ro, debugfs_u32_get, NULL, "0x%08llx\n"); -DEFINE_SIMPLE_ATTRIBUTE(fops_x32_wo, NULL, debugfs_u32_set, "0x%08llx\n"); +DEFINE_DEBUGFS_ATTRIBUTE(fops_x32, debugfs_u32_get, debugfs_u32_set, + "0x%08llx\n"); +DEFINE_DEBUGFS_ATTRIBUTE(fops_x32_ro, debugfs_u32_get, NULL, "0x%08llx\n"); +DEFINE_DEBUGFS_ATTRIBUTE(fops_x32_wo, NULL, debugfs_u32_set, "0x%08llx\n"); -DEFINE_SIMPLE_ATTRIBUTE(fops_x64, debugfs_u64_get, debugfs_u64_set, "0x%016llx\n"); -DEFINE_SIMPLE_ATTRIBUTE(fops_x64_ro, debugfs_u64_get, NULL, "0x%016llx\n"); -DEFINE_SIMPLE_ATTRIBUTE(fops_x64_wo, NULL, debugfs_u64_set, "0x%016llx\n"); +DEFINE_DEBUGFS_ATTRIBUTE(fops_x64, debugfs_u64_get, debugfs_u64_set, + "0x%016llx\n"); +DEFINE_DEBUGFS_ATTRIBUTE(fops_x64_ro, debugfs_u64_get, NULL, "0x%016llx\n"); +DEFINE_DEBUGFS_ATTRIBUTE(fops_x64_wo, NULL, debugfs_u64_set, "0x%016llx\n"); /* * debugfs_create_x{8,16,32,64} - create a debugfs file that is used to read and write an unsigned {8,16,32,64}-bit value @@ -328,7 +605,7 @@ DEFINE_SIMPLE_ATTRIBUTE(fops_x64_wo, NULL, debugfs_u64_set, "0x%016llx\n"); struct dentry *debugfs_create_x8(const char *name, umode_t mode, struct dentry *parent, u8 *value) { - return debugfs_create_mode(name, mode, parent, value, &fops_x8, + return debugfs_create_mode_unsafe(name, mode, parent, value, &fops_x8, &fops_x8_ro, &fops_x8_wo); } EXPORT_SYMBOL_GPL(debugfs_create_x8); @@ -346,7 +623,7 @@ EXPORT_SYMBOL_GPL(debugfs_create_x8); struct dentry *debugfs_create_x16(const char *name, umode_t mode, struct dentry *parent, u16 *value) { - return debugfs_create_mode(name, mode, parent, value, &fops_x16, + return debugfs_create_mode_unsafe(name, mode, parent, value, &fops_x16, &fops_x16_ro, &fops_x16_wo); } EXPORT_SYMBOL_GPL(debugfs_create_x16); @@ -364,7 +641,7 @@ EXPORT_SYMBOL_GPL(debugfs_create_x16); struct dentry *debugfs_create_x32(const char *name, umode_t mode, struct dentry *parent, u32 *value) { - return debugfs_create_mode(name, mode, parent, value, &fops_x32, + return debugfs_create_mode_unsafe(name, mode, parent, value, &fops_x32, &fops_x32_ro, &fops_x32_wo); } EXPORT_SYMBOL_GPL(debugfs_create_x32); @@ -382,7 +659,7 @@ EXPORT_SYMBOL_GPL(debugfs_create_x32); struct dentry *debugfs_create_x64(const char *name, umode_t mode, struct dentry *parent, u64 *value) { - return debugfs_create_mode(name, mode, parent, value, &fops_x64, + return debugfs_create_mode_unsafe(name, mode, parent, value, &fops_x64, &fops_x64_ro, &fops_x64_wo); } EXPORT_SYMBOL_GPL(debugfs_create_x64); @@ -398,10 +675,10 @@ static int debugfs_size_t_get(void *data, u64 *val) *val = *(size_t *)data; return 0; } -DEFINE_SIMPLE_ATTRIBUTE(fops_size_t, debugfs_size_t_get, debugfs_size_t_set, - "%llu\n"); /* %llu and %zu are more or less the same */ -DEFINE_SIMPLE_ATTRIBUTE(fops_size_t_ro, debugfs_size_t_get, NULL, "%llu\n"); -DEFINE_SIMPLE_ATTRIBUTE(fops_size_t_wo, NULL, debugfs_size_t_set, "%llu\n"); +DEFINE_DEBUGFS_ATTRIBUTE(fops_size_t, debugfs_size_t_get, debugfs_size_t_set, + "%llu\n"); /* %llu and %zu are more or less the same */ +DEFINE_DEBUGFS_ATTRIBUTE(fops_size_t_ro, debugfs_size_t_get, NULL, "%llu\n"); +DEFINE_DEBUGFS_ATTRIBUTE(fops_size_t_wo, NULL, debugfs_size_t_set, "%llu\n"); /** * debugfs_create_size_t - create a debugfs file that is used to read and write an size_t value @@ -416,8 +693,9 @@ DEFINE_SIMPLE_ATTRIBUTE(fops_size_t_wo, NULL, debugfs_size_t_set, "%llu\n"); struct dentry *debugfs_create_size_t(const char *name, umode_t mode, struct dentry *parent, size_t *value) { - return debugfs_create_mode(name, mode, parent, value, &fops_size_t, - &fops_size_t_ro, &fops_size_t_wo); + return debugfs_create_mode_unsafe(name, mode, parent, value, + &fops_size_t, &fops_size_t_ro, + &fops_size_t_wo); } EXPORT_SYMBOL_GPL(debugfs_create_size_t); @@ -431,10 +709,12 @@ static int debugfs_atomic_t_get(void *data, u64 *val) *val = atomic_read((atomic_t *)data); return 0; } -DEFINE_SIMPLE_ATTRIBUTE(fops_atomic_t, debugfs_atomic_t_get, +DEFINE_DEBUGFS_ATTRIBUTE(fops_atomic_t, debugfs_atomic_t_get, debugfs_atomic_t_set, "%lld\n"); -DEFINE_SIMPLE_ATTRIBUTE(fops_atomic_t_ro, debugfs_atomic_t_get, NULL, "%lld\n"); -DEFINE_SIMPLE_ATTRIBUTE(fops_atomic_t_wo, NULL, debugfs_atomic_t_set, "%lld\n"); +DEFINE_DEBUGFS_ATTRIBUTE(fops_atomic_t_ro, debugfs_atomic_t_get, NULL, + "%lld\n"); +DEFINE_DEBUGFS_ATTRIBUTE(fops_atomic_t_wo, NULL, debugfs_atomic_t_set, + "%lld\n"); /** * debugfs_create_atomic_t - create a debugfs file that is used to read and @@ -450,8 +730,9 @@ DEFINE_SIMPLE_ATTRIBUTE(fops_atomic_t_wo, NULL, debugfs_atomic_t_set, "%lld\n"); struct dentry *debugfs_create_atomic_t(const char *name, umode_t mode, struct dentry *parent, atomic_t *value) { - return debugfs_create_mode(name, mode, parent, value, &fops_atomic_t, - &fops_atomic_t_ro, &fops_atomic_t_wo); + return debugfs_create_mode_unsafe(name, mode, parent, value, + &fops_atomic_t, &fops_atomic_t_ro, + &fops_atomic_t_wo); } EXPORT_SYMBOL_GPL(debugfs_create_atomic_t); @@ -459,9 +740,17 @@ ssize_t debugfs_read_file_bool(struct file *file, char __user *user_buf, size_t count, loff_t *ppos) { char buf[3]; - bool *val = file->private_data; + bool val; + int r, srcu_idx; - if (*val) + r = debugfs_use_file_start(F_DENTRY(file), &srcu_idx); + if (likely(!r)) + val = *(bool *)file->private_data; + debugfs_use_file_finish(srcu_idx); + if (r) + return r; + + if (val) buf[0] = 'Y'; else buf[0] = 'N'; @@ -477,6 +766,7 @@ ssize_t debugfs_write_file_bool(struct file *file, const char __user *user_buf, char buf[32]; size_t buf_size; bool bv; + int r, srcu_idx; bool *val = file->private_data; buf_size = min(count, (sizeof(buf)-1)); @@ -484,8 +774,14 @@ ssize_t debugfs_write_file_bool(struct file *file, const char __user *user_buf, return -EFAULT; buf[buf_size] = '\0'; - if (strtobool(buf, &bv) == 0) - *val = bv; + if (strtobool(buf, &bv) == 0) { + r = debugfs_use_file_start(F_DENTRY(file), &srcu_idx); + if (likely(!r)) + *val = bv; + debugfs_use_file_finish(srcu_idx); + if (r) + return r; + } return count; } @@ -537,7 +833,7 @@ static const struct file_operations fops_bool_wo = { struct dentry *debugfs_create_bool(const char *name, umode_t mode, struct dentry *parent, bool *value) { - return debugfs_create_mode(name, mode, parent, value, &fops_bool, + return debugfs_create_mode_unsafe(name, mode, parent, value, &fops_bool, &fops_bool_ro, &fops_bool_wo); } EXPORT_SYMBOL_GPL(debugfs_create_bool); @@ -546,8 +842,15 @@ static ssize_t read_file_blob(struct file *file, char __user *user_buf, size_t count, loff_t *ppos) { struct debugfs_blob_wrapper *blob = file->private_data; - return simple_read_from_buffer(user_buf, count, ppos, blob->data, - blob->size); + ssize_t r; + int srcu_idx; + + r = debugfs_use_file_start(F_DENTRY(file), &srcu_idx); + if (likely(!r)) + r = simple_read_from_buffer(user_buf, count, ppos, blob->data, + blob->size); + debugfs_use_file_finish(srcu_idx); + return r; } static const struct file_operations fops_blob = { @@ -584,7 +887,7 @@ struct dentry *debugfs_create_blob(const char *name, umode_t mode, struct dentry *parent, struct debugfs_blob_wrapper *blob) { - return debugfs_create_file(name, mode, parent, blob, &fops_blob); + return debugfs_create_file_unsafe(name, mode, parent, blob, &fops_blob); } EXPORT_SYMBOL_GPL(debugfs_create_blob); @@ -689,7 +992,8 @@ struct dentry *debugfs_create_u32_array(const char *name, umode_t mode, data->array = array; data->elements = elements; - return debugfs_create_file(name, mode, parent, data, &u32_array_fops); + return debugfs_create_file_unsafe(name, mode, parent, data, + &u32_array_fops); } EXPORT_SYMBOL_GPL(debugfs_create_u32_array); diff --git a/fs/debugfs/inode.c b/fs/debugfs/inode.c index 8580831ed237..4bc1f68243c1 100644 --- a/fs/debugfs/inode.c +++ b/fs/debugfs/inode.c @@ -27,9 +27,14 @@ #include <linux/parser.h> #include <linux/magic.h> #include <linux/slab.h> +#include <linux/srcu.h> + +#include "internal.h" #define DEBUGFS_DEFAULT_MODE 0700 +DEFINE_SRCU(debugfs_srcu); + static struct vfsmount *debugfs_mount; static int debugfs_mount_count; static bool debugfs_registered; @@ -39,7 +44,8 @@ static struct inode *debugfs_get_inode(struct super_block *sb) struct inode *inode = new_inode(sb); if (inode) { inode->i_ino = get_next_ino(); - inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME; + inode->i_atime = inode->i_mtime = + inode->i_ctime = current_fs_time(sb); } return inode; } @@ -294,6 +300,37 @@ static struct dentry *end_creating(struct dentry *dentry) return dentry; } +static struct dentry *__debugfs_create_file(const char *name, umode_t mode, + struct dentry *parent, void *data, + const struct file_operations *proxy_fops, + const struct file_operations *real_fops) +{ + struct dentry *dentry; + struct inode *inode; + + if (!(mode & S_IFMT)) + mode |= S_IFREG; + BUG_ON(!S_ISREG(mode)); + dentry = start_creating(name, parent); + + if (IS_ERR(dentry)) + return NULL; + + inode = debugfs_get_inode(dentry->d_sb); + if (unlikely(!inode)) + return failed_creating(dentry); + + inode->i_mode = mode; + inode->i_private = data; + + inode->i_fop = proxy_fops; + dentry->d_fsdata = (void *)real_fops; + + d_instantiate(dentry, inode); + fsnotify_create(d_inode(dentry->d_parent), dentry); + return end_creating(dentry); +} + /** * debugfs_create_file - create a file in the debugfs filesystem * @name: a pointer to a string containing the name of the file to create. @@ -324,29 +361,52 @@ struct dentry *debugfs_create_file(const char *name, umode_t mode, struct dentry *parent, void *data, const struct file_operations *fops) { - struct dentry *dentry; - struct inode *inode; - if (!(mode & S_IFMT)) - mode |= S_IFREG; - BUG_ON(!S_ISREG(mode)); - dentry = start_creating(name, parent); - - if (IS_ERR(dentry)) - return NULL; + return __debugfs_create_file(name, mode, parent, data, + fops ? &debugfs_full_proxy_file_operations : + &debugfs_noop_file_operations, + fops); +} +EXPORT_SYMBOL_GPL(debugfs_create_file); - inode = debugfs_get_inode(dentry->d_sb); - if (unlikely(!inode)) - return failed_creating(dentry); +/** + * debugfs_create_file_unsafe - create a file in the debugfs filesystem + * @name: a pointer to a string containing the name of the file to create. + * @mode: the permission that the file should have. + * @parent: a pointer to the parent dentry for this file. This should be a + * directory dentry if set. If this parameter is NULL, then the + * file will be created in the root of the debugfs filesystem. + * @data: a pointer to something that the caller will want to get to later + * on. The inode.i_private pointer will point to this value on + * the open() call. + * @fops: a pointer to a struct file_operations that should be used for + * this file. + * + * debugfs_create_file_unsafe() is completely analogous to + * debugfs_create_file(), the only difference being that the fops + * handed it will not get protected against file removals by the + * debugfs core. + * + * It is your responsibility to protect your struct file_operation + * methods against file removals by means of debugfs_use_file_start() + * and debugfs_use_file_finish(). ->open() is still protected by + * debugfs though. + * + * Any struct file_operations defined by means of + * DEFINE_DEBUGFS_ATTRIBUTE() is protected against file removals and + * thus, may be used here. + */ +struct dentry *debugfs_create_file_unsafe(const char *name, umode_t mode, + struct dentry *parent, void *data, + const struct file_operations *fops) +{ - inode->i_mode = mode; - inode->i_fop = fops ? fops : &debugfs_file_operations; - inode->i_private = data; - d_instantiate(dentry, inode); - fsnotify_create(d_inode(dentry->d_parent), dentry); - return end_creating(dentry); + return __debugfs_create_file(name, mode, parent, data, + fops ? &debugfs_open_proxy_file_operations : + &debugfs_noop_file_operations, + fops); } -EXPORT_SYMBOL_GPL(debugfs_create_file); +EXPORT_SYMBOL_GPL(debugfs_create_file_unsafe); /** * debugfs_create_file_size - create a file in the debugfs filesystem @@ -461,7 +521,11 @@ struct dentry *debugfs_create_automount(const char *name, inode->i_flags |= S_AUTOMOUNT; inode->i_private = data; dentry->d_fsdata = (void *)f; + /* directory inodes start off with i_nlink == 2 (for "." entry) */ + inc_nlink(inode); d_instantiate(dentry, inode); + inc_nlink(d_inode(dentry->d_parent)); + fsnotify_mkdir(d_inode(dentry->d_parent), dentry); return end_creating(dentry); } EXPORT_SYMBOL(debugfs_create_automount); @@ -565,6 +629,8 @@ void debugfs_remove(struct dentry *dentry) inode_unlock(d_inode(parent)); if (!ret) simple_release_fs(&debugfs_mount, &debugfs_mount_count); + + synchronize_srcu(&debugfs_srcu); } EXPORT_SYMBOL_GPL(debugfs_remove); @@ -642,6 +708,8 @@ void debugfs_remove_recursive(struct dentry *dentry) if (!__debugfs_remove(child, parent)) simple_release_fs(&debugfs_mount, &debugfs_mount_count); inode_unlock(d_inode(parent)); + + synchronize_srcu(&debugfs_srcu); } EXPORT_SYMBOL_GPL(debugfs_remove_recursive); diff --git a/fs/debugfs/internal.h b/fs/debugfs/internal.h new file mode 100644 index 000000000000..bba52634b995 --- /dev/null +++ b/fs/debugfs/internal.h @@ -0,0 +1,26 @@ +/* + * internal.h - declarations internal to debugfs + * + * Copyright (C) 2016 Nicolai Stange <nicstange@gmail.com> + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License version + * 2 as published by the Free Software Foundation. + * + */ + +#ifndef _DEBUGFS_INTERNAL_H_ +#define _DEBUGFS_INTERNAL_H_ + +struct file_operations; + +/* declared over in file.c */ +extern const struct file_operations debugfs_noop_file_operations; +extern const struct file_operations debugfs_open_proxy_file_operations; +extern const struct file_operations debugfs_full_proxy_file_operations; + +struct dentry *debugfs_create_file_unsafe(const char *name, umode_t mode, + struct dentry *parent, void *data, + const struct file_operations *fops); + +#endif /* _DEBUGFS_INTERNAL_H_ */ |