From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752159AbbJLJ34 (ORCPT ); Mon, 12 Oct 2015 05:29:56 -0400 Received: from mailout2.w1.samsung.com ([210.118.77.12]:54344 "EHLO mailout2.w1.samsung.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751439AbbJLJ3y (ORCPT ); Mon, 12 Oct 2015 05:29:54 -0400 X-AuditID: cbfec7f4-f79c56d0000012ee-ae-561b7d8e675a From: Paul Osmialowski To: Jonathan Corbet , Arnd Bergmann , Andrew Morton , Petr Mladek , Greg Kroah-Hartman , Daniel Mack , Kay Sievers , Joe Perches , Tejun Heo , linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-api@vger.kernel.org Cc: Marcin Niesluchowski , Karol Lewandowski , Paul Osmialowski , Bartlomiej Zolnierkiewicz , Shuah Khan Subject: [RFC v2 8/9] kmsg: add ioctl for kmsg* devices operating on buffers Date: Mon, 12 Oct 2015 11:29:16 +0200 Message-id: <1444642157-32618-9-git-send-email-p.osmialowsk@samsung.com> X-Mailer: git-send-email 1.9.1 In-reply-to: <1444642157-32618-1-git-send-email-p.osmialowsk@samsung.com> References: <1444642157-32618-1-git-send-email-p.osmialowsk@samsung.com> X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFnrBLMWRmVeSWpSXmKPExsVy+t/xy7p9tdJhBkd7TS3mrF/DZvF30jF2 i40z1rNaPDnQzmjR9PcVi0Xz4vVsFrPvP2axaPw0l9ni8oZzbBabv3ewWSxsW8JicXnXHDaL Q2d/sFhMeHOA2WLh/81MFlO/fGCx+LX8KKODoMfvX5MYPTat6mTzODHjN4vH/rlr2D0W901m 9djSf5fd48uqa8wefVtWMXqcWXCE3ePzJjmPj+s9PbbvXs4SwBPFZZOSmpNZllqkb5fAlfH1 1nmmglX2FVtuHGRtYHxp1MXIySEhYCJxfF07E4QtJnHh3nq2LkYuDiGBpYwSZ1/NZYdwGpkk vm9azA5SxSZgKHHz/2FGkISIwFxmieZfC1hBHGaBT4wSP9YuB6ri4BAW8JFoupIK0sAioCrR Oe8MK0iYV8BDYuu+ZIhtchInj01mBbE5BTwl/p5dD3aFEFDJ460tTBMYeRcwMqxiFE0tTS4o TkrPNdQrTswtLs1L10vOz93ECAn/LzsYFx+zOsQowMGoxMPLsUUqTIg1say4MvcQowQHs5II 794g6TAh3pTEyqrUovz4otKc1OJDjNIcLErivHN3vQ8REkhPLEnNTk0tSC2CyTJxcEo1MG46 +mfBZdtwod981a1ayXbsx3R/q6zhyfwqsiFv5kmPzMM9jOvO2F7ctarTK2DGeZNDi+I4yqbm /l/4P7lWKDjielPNmvY9EbmnFdv6BYMiTdwi7nyYvpE3qehb0ObNrGkzm932zpuRd+C0R2nM p++3zK/u3Pdo4h2dioQDc99+U7XfsCSpnEuJpTgj0VCLuag4EQDi1Ch3ewIAAA== Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Marcin Niesluchowski There is no possibility to clear additional kmsg buffers, get size of them or know what size should be passed to read file operation (too small size causes it to retrun -EINVAL). Add following ioctls which solve those issues: * KMSG_CMD_GET_BUF_SIZE * KMSG_CMD_GET_READ_SIZE_MAX * KMSG_CMD_CLEAR Signed-off-by: Marcin Niesluchowski --- Documentation/ioctl/ioctl-number.txt | 2 +- include/uapi/linux/kmsg_ioctl.h | 15 ++++++ kernel/printk/printk.c | 102 ++++++++++++++++++++++++++--------- 3 files changed, 92 insertions(+), 27 deletions(-) diff --git a/Documentation/ioctl/ioctl-number.txt b/Documentation/ioctl/ioctl-number.txt index a36dc46..c55e49e 100644 --- a/Documentation/ioctl/ioctl-number.txt +++ b/Documentation/ioctl/ioctl-number.txt @@ -316,7 +316,7 @@ Code Seq#(hex) Include File Comments 0xB1 00-1F PPPoX 0xB3 00 linux/mmc/ioctl.h -0xBB 00-02 uapi/linux/kmsg_ioctl.h +0xBB 00-83 uapi/linux/kmsg_ioctl.h 0xC0 00-0F linux/usb/iowarrior.h 0xCA 00-0F uapi/misc/cxl.h 0xCA 80-8F uapi/scsi/cxlflash_ioctl.h diff --git a/include/uapi/linux/kmsg_ioctl.h b/include/uapi/linux/kmsg_ioctl.h index 89c0c61..2389d9f 100644 --- a/include/uapi/linux/kmsg_ioctl.h +++ b/include/uapi/linux/kmsg_ioctl.h @@ -27,4 +27,19 @@ 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 be08aae..1bc4a31 100644 --- a/kernel/printk/printk.c +++ b/kernel/printk/printk.c @@ -262,6 +262,10 @@ 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 @@ -279,10 +283,6 @@ 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) @@ -306,6 +306,8 @@ 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, }; @@ -1116,18 +1118,14 @@ 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'. Reading /dev/kmsg itself - * changes no global state, and does not clear anything. + * like issued by 'dmesg -c' or KMSG_CMD_CLEAR ioctl + * command. Reading /dev/kmsg itself changes no global + * state, and does not clear anything. */ - user->idx = clear_idx; - user->seq = clear_seq; + user->idx = log_b->clear_idx; + user->seq = log_b->clear_seq; break; case SEEK_END: /* after the last record */ @@ -1267,6 +1265,56 @@ 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; @@ -1285,6 +1333,8 @@ 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, }; @@ -1889,18 +1939,18 @@ static int syslog_print_all(char __user *buf, int size, bool clear) u32 idx; enum log_flags prev; - if (clear_seq < log_buf.first_seq) { + if (log_buf.clear_seq < log_buf.first_seq) { /* messages are gone, move to first available one */ - clear_seq = log_buf.first_seq; - clear_idx = log_buf.first_idx; + log_buf.clear_seq = log_buf.first_seq; + log_buf.clear_idx = log_buf.first_idx; } /* * Find first record that fits, including all following records, * into the user-provided buffer for this dump. */ - seq = clear_seq; - idx = clear_idx; + seq = log_buf.clear_seq; + idx = log_buf.clear_idx; prev = 0; while (seq < log_buf.next_seq) { struct printk_log *msg = log_from_idx(&log_buf, idx); @@ -1912,8 +1962,8 @@ static int syslog_print_all(char __user *buf, int size, bool clear) } /* move first record forward until length fits into the buffer */ - seq = clear_seq; - idx = clear_idx; + seq = log_buf.clear_seq; + idx = log_buf.clear_idx; prev = 0; while (len > size && seq < log_buf.next_seq) { struct printk_log *msg = log_from_idx(&log_buf, idx); @@ -1959,8 +2009,8 @@ static int syslog_print_all(char __user *buf, int size, bool clear) } if (clear) { - clear_seq = log_buf.next_seq; - clear_idx = log_buf.next_idx; + log_buf.clear_seq = log_buf.next_seq; + log_buf.clear_idx = log_buf.next_idx; } raw_spin_unlock_irq(&log_buf.lock); @@ -3341,8 +3391,8 @@ void kmsg_dump(enum kmsg_dump_reason reason) dumper->active = true; raw_spin_lock_irqsave(&log_buf.lock, flags); - dumper->cur_seq = clear_seq; - dumper->cur_idx = clear_idx; + dumper->cur_seq = log_buf.clear_seq; + dumper->cur_idx = log_buf.clear_idx; dumper->next_seq = log_buf.next_seq; dumper->next_idx = log_buf.next_idx; raw_spin_unlock_irqrestore(&log_buf.lock, flags); @@ -3548,8 +3598,8 @@ EXPORT_SYMBOL_GPL(kmsg_dump_get_buffer); */ void kmsg_dump_rewind_nolock(struct kmsg_dumper *dumper) { - dumper->cur_seq = clear_seq; - dumper->cur_idx = clear_idx; + dumper->cur_seq = log_buf.clear_seq; + dumper->cur_idx = log_buf.clear_idx; dumper->next_seq = log_buf.next_seq; dumper->next_idx = log_buf.next_idx; } -- 1.9.1