Revert "kmsg: add ioctl for kmsg* devices operating on buffers"

This reverts commit a6b3b517a1b5ce5faab04d2a4ba1dc05a9e8fa7a.

diff --git a/Documentation/ioctl/ioctl-number.txt b/Documentation/ioctl/ioctl-number.txt
index 67a94ca348bdbb33527e3c5aab08dd037b7e91d6..5258759bb0ff2ada60c36c962c542348bf1fa3e2 100644 (file)
--- a/Documentation/ioctl/ioctl-number.txt
+++ b/Documentation/ioctl/ioctl-number.txt
@@ -313,7 +313,7 @@ Code  Seq#(hex)     Include File            Comments
                                        <mailto:vgo@ratio.de>
 0xB1   00-1F   PPPoX                   <mailto:mostrows@styx.uwaterloo.ca>
 0xB3   00      linux/mmc/ioctl.h
-0xBB   00-83   uapi/linux/kmsg_ioctl.h
+0xBB   00-02   uapi/linux/kmsg_ioctl.h
 0xC0   00-0F   linux/usb/iowarrior.h
 0xCA   00-0F   uapi/misc/cxl.h
 0xCB   00-1F   CBM serial IEC bus      in development:

diff --git a/include/uapi/linux/kmsg_ioctl.h b/include/uapi/linux/kmsg_ioctl.h
index 2389d9f09706164aeccdb8058aee0b8152c8adbe..89c0c615c4ea77d294bfe437563c05780f80ce12 100644 (file)
--- a/include/uapi/linux/kmsg_ioctl.h
+++ b/include/uapi/linux/kmsg_ioctl.h
@@ -27,19 +27,4 @@ struct kmsg_cmd_buffer_add {
                                              struct kmsg_cmd_buffer_add)
 #define KMSG_CMD_BUFFER_DEL            _IOW(KMSG_IOCTL_MAGIC, 0x01, int)
 
-/*
- * A ioctl interface for kmsg* devices.
- *
- * KMSG_CMD_GET_BUF_SIZE:      Retrieve cyclic log buffer size associated with
- *                             device.
- * KMSG_CMD_GET_READ_SIZE_MAX: Retrieve max size of data read by kmsg read
- *                             operation.
- * KMSG_CMD_CLEAR:             Clears cyclic log buffer. After that operation
- *                             there is no data to read from buffer unless
- *                             logs are written.
- */
-#define KMSG_CMD_GET_BUF_SIZE          _IOR(KMSG_IOCTL_MAGIC, 0x80, __u32)
-#define KMSG_CMD_GET_READ_SIZE_MAX     _IOR(KMSG_IOCTL_MAGIC, 0x81, __u32)
-#define KMSG_CMD_CLEAR                 _IO(KMSG_IOCTL_MAGIC, 0x82)
-
 #endif

diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index d6b96136deb4141f07e32f9d768e8e622a518b31..944a81ae1ecf42efff9666bd532fde3dbca3ba94 100644 (file)
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -254,10 +254,6 @@ struct log_buffer {
        u64 next_seq;
 #ifdef CONFIG_PRINTK
        u32 next_idx;           /* index of the next record to store */
-/* sequence number of the next record to read after last 'clear' command */
-       u64 clear_seq;
-/* index of the next record to read after last 'clear' command */
-       u32 clear_idx;
        int mode;               /* mode of device */
        int minor;              /* minor representing buffer device */
 #endif
@@ -275,6 +271,10 @@ static u64 console_seq;
 static u32 console_idx;
 static enum log_flags console_prev;
 
+/* the next printk record to read after the last 'clear' command */
+static u64 clear_seq;
+static u32 clear_idx;
+
 #define PREFIX_MAX             32
 #define LOG_LINE_MAX           (1024 - PREFIX_MAX)
 #define KMSG_NUM_MAX    255
@@ -295,8 +295,6 @@ static struct log_buffer log_buf = {
        .first_idx      = 0,
        .next_seq       = 0,
        .next_idx       = 0,
-       .clear_seq      = 0,
-       .clear_idx      = 0,
        .mode           = 0,
        .minor          = 0,
 };
@@ -1094,14 +1092,18 @@ static loff_t kmsg_llseek(struct log_buffer *log_b, struct file *file,
                user->seq = log_b->first_seq;
                break;
        case SEEK_DATA:
+               /* no clear index for kmsg_sys buffers */
+               if (log_b != &log_buf) {
+                       ret = -EINVAL;
+                       break;
+               }
                /*
                 * The first record after the last SYSLOG_ACTION_CLEAR,
-                * like issued by 'dmesg -c' or KMSG_CMD_CLEAR ioctl
-                * command. Reading /dev/kmsg itself changes no global
-                * state, and does not clear anything.
+                * like issued by 'dmesg -c'. Reading /dev/kmsg itself
+                * changes no global state, and does not clear anything.
                 */
-               user->idx = log_b->clear_idx;
-               user->seq = log_b->clear_seq;
+               user->idx = clear_idx;
+               user->seq = clear_seq;
                break;
        case SEEK_END:
                /* after the last record */
@@ -1248,56 +1250,6 @@ static int devkmsg_open(struct inode *inode, struct file *file)
        return ret;
 }
 
-static long kmsg_ioctl(struct log_buffer *log_b, unsigned int cmd,
-                      unsigned long arg)
-{
-       void __user *argp = (void __user *)arg;
-       static const u32 read_size_max = CONSOLE_EXT_LOG_MAX;
-
-       switch (cmd) {
-       case KMSG_CMD_GET_BUF_SIZE:
-               if (copy_to_user(argp, &log_b->len, sizeof(u32)))
-                       return -EFAULT;
-               break;
-       case KMSG_CMD_GET_READ_SIZE_MAX:
-               if (copy_to_user(argp, &read_size_max, sizeof(u32)))
-                       return -EFAULT;
-               break;
-       case KMSG_CMD_CLEAR:
-               if (!capable(CAP_SYSLOG))
-                       return -EPERM;
-               raw_spin_lock_irq(&log_b->lock);
-               log_b->clear_seq = log_b->next_seq;
-               log_b->clear_idx = log_b->next_idx;
-               raw_spin_unlock_irq(&log_b->lock);
-               break;
-       default:
-               return -ENOTTY;
-       }
-       return 0;
-}
-
-static long devkmsg_ioctl(struct file *file, unsigned int cmd,
-                         unsigned long arg)
-{
-       long ret = -ENXIO;
-       int minor = iminor(file->f_inode);
-       struct log_buffer *log_b;
-
-       if (minor == log_buf.minor)
-               return kmsg_ioctl(&log_buf, cmd, arg);
-
-       rcu_read_lock();
-       list_for_each_entry_rcu(log_b, &log_buf.list, list) {
-               if (log_b->minor == minor) {
-                       ret = kmsg_ioctl(log_b, cmd, arg);
-                       break;
-               }
-       }
-       rcu_read_unlock();
-       return ret;
-}
-
 static int devkmsg_release(struct inode *inode, struct file *file)
 {
        struct devkmsg_user *user = file->private_data;
@@ -1316,8 +1268,6 @@ const struct file_operations kmsg_fops = {
        .write_iter = devkmsg_write,
        .llseek = devkmsg_llseek,
        .poll = devkmsg_poll,
-       .unlocked_ioctl = devkmsg_ioctl,
-       .compat_ioctl = devkmsg_ioctl,
        .release = devkmsg_release,
 };
 
@@ -1922,18 +1872,18 @@ static int syslog_print_all(char __user *buf, int size, bool clear)
                u32 idx;
                enum log_flags prev;
 
-               if (log_buf.clear_seq < log_buf.first_seq) {
+               if (clear_seq < log_buf.first_seq) {
                        /* messages are gone, move to first available one */
-                       log_buf.clear_seq = log_buf.first_seq;
-                       log_buf.clear_idx = log_buf.first_idx;
+                       clear_seq = log_buf.first_seq;
+                       clear_idx = log_buf.first_idx;
                }
 
                /*
                 * Find first record that fits, including all following records,
                 * into the user-provided buffer for this dump.
                 */
-               seq = log_buf.clear_seq;
-               idx = log_buf.clear_idx;
+               seq = clear_seq;
+               idx = clear_idx;
                prev = 0;
                while (seq < log_buf.next_seq) {
                        struct printk_log *msg = log_from_idx(&log_buf, idx);
@@ -1945,8 +1895,8 @@ static int syslog_print_all(char __user *buf, int size, bool clear)
                }
 
                /* move first record forward until length fits into the buffer */
-               seq = log_buf.clear_seq;
-               idx = log_buf.clear_idx;
+               seq = clear_seq;
+               idx = clear_idx;
                prev = 0;
                while (len > size && seq < log_buf.next_seq) {
                        struct printk_log *msg = log_from_idx(&log_buf, idx);
@@ -1992,8 +1942,8 @@ static int syslog_print_all(char __user *buf, int size, bool clear)
        }
 
        if (clear) {
-               log_buf.clear_seq = log_buf.next_seq;
-               log_buf.clear_idx = log_buf.next_idx;
+               clear_seq = log_buf.next_seq;
+               clear_idx = log_buf.next_idx;
        }
        raw_spin_unlock_irq(&log_buf.lock);
 
@@ -3373,8 +3323,8 @@ void kmsg_dump(enum kmsg_dump_reason reason)
                dumper->active = true;
 
                raw_spin_lock_irqsave(&log_buf.lock, flags);
-               dumper->cur_seq = log_buf.clear_seq;
-               dumper->cur_idx = log_buf.clear_idx;
+               dumper->cur_seq = clear_seq;
+               dumper->cur_idx = clear_idx;
                dumper->next_seq = log_buf.next_seq;
                dumper->next_idx = log_buf.next_idx;
                raw_spin_unlock_irqrestore(&log_buf.lock, flags);
@@ -3580,8 +3530,8 @@ EXPORT_SYMBOL_GPL(kmsg_dump_get_buffer);
  */
 void kmsg_dump_rewind_nolock(struct kmsg_dumper *dumper)
 {
-       dumper->cur_seq = log_buf.clear_seq;
-       dumper->cur_idx = log_buf.clear_idx;
+       dumper->cur_seq = clear_seq;
+       dumper->cur_idx = clear_idx;
        dumper->next_seq = log_buf.next_seq;
        dumper->next_idx = log_buf.next_idx;
 }