From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754003AbbJ0Kb1 (ORCPT ); Tue, 27 Oct 2015 06:31:27 -0400 Received: from mailout3.w1.samsung.com ([210.118.77.13]:37497 "EHLO mailout3.w1.samsung.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754050AbbJ0K3J (ORCPT ); Tue, 27 Oct 2015 06:29:09 -0400 X-AuditID: cbfec7f5-f794b6d000001495-40-562f51ed5b4b 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: Richard Weinberger , Marcin Niesluchowski , Karol Lewandowski , Paul Osmialowski , Bartlomiej Zolnierkiewicz , Shuah Khan , Andy Lutomirski Subject: [RFC v5 5/8] kmsg: add function for adding and deleting additional buffers Date: Tue, 27 Oct 2015 11:28:40 +0100 Message-id: <1445941723-20388-6-git-send-email-p.osmialowsk@samsung.com> X-Mailer: git-send-email 1.9.1 In-reply-to: <1445941723-20388-1-git-send-email-p.osmialowsk@samsung.com> References: <1445941723-20388-1-git-send-email-p.osmialowsk@samsung.com> X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFvrNLMWRmVeSWpSXmKPExsVy+t/xy7pvA/XDDOYu5LGYs34Nm8XfScfY LTbOWM9q8eRAO6NF099XLBbNi9ezWcy+/5jFovHTXGaLyxvOsVls/t7BZrGwbQmLxeVdc9gs Vq9tYLU4dPYHi8WENweYLRb+38xk8WHiBjaLqV8+sFj8Wn6U0UHY4/6bvywev39NYvTYOesu u8emVZ1sHidm/Gbx2D93DbvH4r7JrB5b+oESX1ZdY/bo27KK0ePMgiPsHp83yXl8XO/psX33 cpYAvigum5TUnMyy1CJ9uwSujPtbt7IVnDCtmNpxkLmB8b52FyMHh4SAicSaBQpdjJxAppjE hXvr2UBsIYGljBLzdxt1MXIB2Y1MEt/2b2UBSbAJGErc/H+YESQhIjCXWaL51wJWEIdZ4ByT xOpde5lApgoLhEq0rckEaWARUJU4/WATI4jNK+Ah0fT4LxvENjmJk8cms4LYnAKeEk0Tb7FA bPaQWNq+n3UCI+8CRoZVjKKppckFxUnpuUZ6xYm5xaV56XrJ+bmbGCFR8nUH49JjVocYBTgY lXh4DSr0woRYE8uKK3MPMUpwMCuJ8Arq6IcJ8aYkVlalFuXHF5XmpBYfYpTmYFES5525632I kEB6YklqdmpqQWoRTJaJg1OqgVHoJdfd2jmlAqFswTI3FIO3nf77svtx/5qaR1OELrSf2zXz QuwK667kNZs+m9yUiVuj/k+x585cEXn7XM3ZXbo/Ny7c8l53yiIznSklF32/PN5fEvyA58XV YuGayZvKHpQLK3LvvhO1ceqeexdvxPWnhE7n5hHmXVjZ9EKw52hP+D5tibTyibeVWIozEg21 mIuKEwHrbGMKjgIAAA== Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Marcin Niesluchowski Additional kmsg buffers should be created and deleted dynamically. Adding two functions * kmsg_sys_buffer_add() creates additional kmsg buffer returning minor * kmsg_sys_buffer_del() deletes one based on provided minor Signed-off-by: Marcin Niesluchowski Signed-off-by: Paul Osmialowski --- include/linux/printk.h | 9 +++++ kernel/printk/kmsg.c | 107 +++++++++++++++++++++++++++++++++++++++++++++++-- kernel/printk/printk.c | 12 ++++++ kernel/printk/printk.h | 4 ++ 4 files changed, 129 insertions(+), 3 deletions(-) diff --git a/include/linux/printk.h b/include/linux/printk.h index 0c4f9de..513fa6f 100644 --- a/include/linux/printk.h +++ b/include/linux/printk.h @@ -431,6 +431,8 @@ extern const struct file_operations kmsg_fops; extern struct device *init_kmsg(int minor, umode_t mode); extern int kmsg_memory_open(struct inode *inode, struct file *filp); extern int kmsg_mode(int minor, umode_t *mode); +extern int kmsg_sys_buffer_add(size_t size, umode_t mode); +extern void kmsg_sys_buffer_del(int minor); #else @@ -449,6 +451,13 @@ static inline int kmsg_mode(int minor, umode_t *mode) return -ENXIO; } +static inline int kmsg_sys_buffer_add(size_t size, umode_t mode) +{ + return -ENXIO; +} + +static inline void kmsg_sys_buffer_del(int minor) {} + #endif enum { diff --git a/kernel/printk/kmsg.c b/kernel/printk/kmsg.c index 726250f..9222fdc 100644 --- a/kernel/printk/kmsg.c +++ b/kernel/printk/kmsg.c @@ -19,6 +19,7 @@ #include #include #include +#include #include @@ -141,8 +142,20 @@ static ssize_t kmsg_read(struct log_buffer *log_b, struct file *file, } raw_spin_unlock_irq(&log_b->lock); - ret = wait_event_interruptible(log_b->wait, - user->seq != log_b->next_seq); + if (log_b == &log_buf) { + ret = wait_event_interruptible(log_b->wait, + user->seq != log_b->next_seq); + } else { + rcu_read_unlock(); + kref_get(&log_b->refcount); + ret = wait_event_interruptible(log_b->wait, + user->seq != log_b->next_seq); + if (log_b->minor == -1) + ret = -ENXIO; + if (kref_put(&log_b->refcount, log_buf_release)) + ret = -ENXIO; + rcu_read_lock(); + } if (ret) goto out; raw_spin_lock_irq(&log_b->lock); @@ -311,8 +324,14 @@ static unsigned int devkmsg_poll(struct file *file, poll_table *wait) rcu_read_lock(); list_for_each_entry_rcu(log_b, &log_buf.list, list) { if (log_b->minor == minor) { + kref_get(&log_b->refcount); + rcu_read_unlock(); + ret = kmsg_poll(log_b, file, wait); - break; + + if (kref_put(&log_b->refcount, log_buf_release)) + return POLLERR|POLLNVAL; + return ret; } } rcu_read_unlock(); @@ -428,6 +447,88 @@ int kmsg_mode(int minor, umode_t *mode) return ret; } +static DEFINE_SPINLOCK(kmsg_sys_list_lock); + +int kmsg_sys_buffer_add(size_t size, umode_t mode) +{ + unsigned long flags; + int minor = log_buf.minor; + struct log_buffer *log_b; + struct log_buffer *log_b_new; + + if (size < LOG_LINE_MAX + PREFIX_MAX) + return -EINVAL; + + log_b_new = kzalloc(sizeof(struct log_buffer), GFP_KERNEL); + if (!log_b_new) + return -ENOMEM; + + log_b_new->buf = kmalloc(size, GFP_KERNEL); + if (!log_b_new->buf) { + kfree(log_b_new); + return -ENOMEM; + } + + log_b_new->len = size; + log_b_new->lock = __RAW_SPIN_LOCK_UNLOCKED(log_b_new->lock); + init_waitqueue_head(&log_b_new->wait); + kref_init(&log_b_new->refcount); + log_b_new->mode = mode; + + kref_get(&log_b_new->refcount); + + spin_lock_irqsave(&kmsg_sys_list_lock, flags); + + list_for_each_entry(log_b, &log_buf.list, list) { + if (log_b->minor - minor > 1) + break; + + minor = log_b->minor; + } + + if (!(minor & MINORMASK)) { + kref_put(&log_b->refcount, log_buf_release); + spin_unlock_irqrestore(&kmsg_sys_list_lock, flags); + return -ERANGE; + } + + minor += 1; + log_b_new->minor = minor; + + list_add_tail_rcu(&log_b_new->list, &log_b->list); + + spin_unlock_irqrestore(&kmsg_sys_list_lock, flags); + + return minor; +} + +void kmsg_sys_buffer_del(int minor) +{ + unsigned long flags; + struct log_buffer *log_b; + + spin_lock_irqsave(&kmsg_sys_list_lock, flags); + + list_for_each_entry(log_b, &log_buf.list, list) { + if (log_b->minor == minor) + break; + } + + if (log_b == &log_buf) { + spin_unlock_irqrestore(&kmsg_sys_list_lock, flags); + return; + } + + list_del_rcu(&log_b->list); + + spin_unlock_irqrestore(&kmsg_sys_list_lock, flags); + + log_b->minor = -1; + wake_up_interruptible(&log_b->wait); + + kref_put(&log_b->refcount, log_buf_release); +} + static DEFINE_SPINLOCK(dump_list_lock); static LIST_HEAD(dump_list); diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c index fed50da..405fe79 100644 --- a/kernel/printk/printk.c +++ b/kernel/printk/printk.c @@ -41,6 +41,8 @@ #include #include #include +#include +#include #include @@ -173,6 +175,7 @@ struct log_buffer log_buf = { .len = __LOG_BUF_K_LEN, .lock = __RAW_SPIN_LOCK_UNLOCKED(log_buf.lock), .wait = __WAIT_QUEUE_HEAD_INITIALIZER(log_buf.wait), + .refcount = { .refcount = { .counter = 0 } }, .first_seq = 0, .first_idx = 0, .next_seq = 0, @@ -218,6 +221,15 @@ u32 log_buf_len_get(void) return log_buf.len; } +void log_buf_release(struct kref *ref) +{ + struct log_buffer *log_b = container_of(ref, struct log_buffer, + refcount); + + kfree(log_b->buf); + kfree(log_b); +} + /* * Check whether there is enough free space for the given message. * diff --git a/kernel/printk/printk.h b/kernel/printk/printk.h index f9e3220..85c733f 100644 --- a/kernel/printk/printk.h +++ b/kernel/printk/printk.h @@ -5,6 +5,7 @@ #include #include #include +#include #ifdef CONFIG_PRINTK @@ -108,6 +109,7 @@ struct log_buffer { char *buf; /* cyclic log buffer */ u32 len; /* buffer length */ wait_queue_head_t wait; /* wait queue for kmsg buffer */ + struct kref refcount; /* refcount for kmsg_sys buffers */ #endif /* * The lock protects kmsg buffer, indices, counters. This can be taken within @@ -136,6 +138,8 @@ struct log_buffer { extern struct log_buffer log_buf; +void log_buf_release(struct kref *ref); + ssize_t msg_print_ext_header(char *buf, size_t size, struct printk_log *msg, u64 seq, enum log_flags prev_flags); -- 1.9.1