Return-Path: Date: Thu, 23 Jul 2015 08:52:14 +0200 From: Alexander Aring To: Lukasz Duda Cc: linux-wpan@vger.kernel.org, linux-bluetooth@vger.kernel.org, Glenn Ruben Bakke Subject: Re: [RFC v2 2/4] 6lowpan: Add stateful compression component of 6lowpan module Message-ID: <20150723065209.GB1941@omega> References: <1436788233-13960-1-git-send-email-lukasz.duda@nordicsemi.no> <1436788233-13960-3-git-send-email-lukasz.duda@nordicsemi.no> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 In-Reply-To: <1436788233-13960-3-git-send-email-lukasz.duda@nordicsemi.no> Sender: linux-wpan-owner@vger.kernel.org List-ID: Hi, On Mon, Jul 13, 2015 at 01:50:31PM +0200, Lukasz Duda wrote: > The patch adds stateful compression (context ids based compression) to > the 6lowpan module [RFC6282]. > > Stateful Compression users allocate context tables through the functions > in the context.c using public APIs declared in 6lowpan.h. The context.c > is extending the 6lowpan module and not created as a separate module. > > A debugfs entry for maintaining the context tables is implemented > (/sys/kernel/debug/6lowpan/context). > > Example usage of the 6lowpan debugfs interface: > > echo " > " > /sys/kernel/debug/6lowpan/context > > Examples: > > echo "add bt0 3 2001:db8:: 64 1" > /sys/kernel/debug/6lowpan/context > > echo "remove bt0 3" > /sys/kernel/debug/6lowpan/context > > cat /sys/kernel/debug/6lowpan/context > > e.g. > Context table of interface bt0 > > CID Prefix Len CF > 3 2001:db8:: 64 1 > 4 2001:db8::1 128 1 > I tried to test it and I got a: [ 132.092412] ================================= [ 132.096976] [ INFO: inconsistent lock state ] [ 132.101545] 4.1.0-268283-gca74796 #9 Tainted: G W [ 132.107650] --------------------------------- [ 132.112214] inconsistent {IN-SOFTIRQ-W} -> {SOFTIRQ-ON-W} usage. [ 132.118506] sh/1254 [HC0[0]:SC0[0]:HE1:SE1] takes: [ 132.123525] (module_lock){+.?...}, at: [] get_table+0x14/0x5c [6lowpan] [ 132.131536] {IN-SOFTIRQ-W} state was registered at: [ 132.136645] [] _raw_spin_lock+0x30/0x40 [ 132.141785] [] get_table+0x14/0x5c [6lowpan] [ 132.147372] [] lowpan_context_compress+0x24/0x1d8 [6lowpan] [ 132.154324] [] lowpan_header_compress+0x68/0x6c0 [6lowpan] [ 132.161175] [] lowpan_header+0x84/0x250 [ieee802154_6lowpan] [ 132.168220] [] lowpan_xmit+0x68/0x344 [ieee802154_6lowpan] [ 132.175070] [] dev_hard_start_xmit+0x2a8/0x498 [ 132.180829] [] __dev_queue_xmit+0x660/0x798 [ 132.186315] [] ip6_finish_output2+0x320/0xbb0 [ipv6] [ 132.192845] [] ip6_output+0x6c/0x2c8 [ipv6] [ 132.198412] [] mld_sendpack+0x32c/0x89c [ipv6] [ 132.204318] [] mld_ifc_timer_expire+0x1d4/0x304 [ipv6] [ 132.210929] [] call_timer_fn+0x7c/0x180 [ 132.216055] [] run_timer_softirq+0x170/0x2b4 [ 132.221626] [] __do_softirq+0x138/0x340 [ 132.226755] [] irq_exit+0xbc/0x130 [ 132.231417] [] __handle_domain_irq+0x6c/0xe0 [ 132.237004] [] omap_intc_handle_irq+0xa8/0xb8 [ 132.242673] [] __irq_svc+0x44/0x5c [ 132.247340] [] __mutex_unlock_slowpath+0x10c/0x1a4 [ 132.253462] [] __mutex_unlock_slowpath+0x10c/0x1a4 [ 132.259586] [] unlock_rename+0x18/0x40 [ 132.264630] [] SyS_renameat2+0x258/0x4d0 [ 132.269844] [] SyS_rename+0x28/0x30 [ 132.274601] [] ret_fast_syscall+0x0/0x54 [ 132.279821] irq event stamp: 76337 [ 132.283380] hardirqs last enabled at (76337): [] ret_fast_syscall+0x2c/0x54 [ 132.291686] hardirqs last disabled at (76336): [] ret_fast_syscall+0xc/0x54 [ 132.299896] softirqs last enabled at (75714): [] __do_softirq+0x29c/0x340 [ 132.308017] softirqs last disabled at (75709): [] irq_exit+0xbc/0x130 [ 132.315683] [ 132.315683] other info that might help us debug this: [ 132.322515] Possible unsafe locking scenario: [ 132.322515] [ 132.328712] CPU0 [ 132.331274] ---- [ 132.333833] lock(module_lock); [ 132.337228] [ 132.339970] lock(module_lock); [ 132.343547] [ 132.343547] *** DEADLOCK *** [ 132.343547] [ 132.349752] 1 lock held by sh/1254: [ 132.353401] #0: (sb_writers#9){.+.+.+}, at: [] vfs_write+0x13c/0x164 [ 132.361210] [ 132.361210] stack backtrace: [ 132.365788] CPU: 0 PID: 1254 Comm: sh Tainted: G W 4.1.0-268283-gca74796 #9 [ 132.374257] Hardware name: Generic AM33XX (Flattened Device Tree) [ 132.380663] [] (unwind_backtrace) from [] (show_stack+0x10/0x14) [ 132.388777] [] (show_stack) from [] (dump_stack+0x84/0x9c) [ 132.396363] [] (dump_stack) from [] (print_usage_bug+0x1d8/0x2cc) [ 132.404572] [] (print_usage_bug) from [] (mark_lock+0x1dc/0x6c4) [ 132.412690] [] (mark_lock) from [] (__lock_acquire+0x860/0x2048) [ 132.420809] [] (__lock_acquire) from [] (lock_acquire+0xa8/0x124) [ 132.429016] [] (lock_acquire) from [] (_raw_spin_lock+0x30/0x40) [ 132.437147] [] (_raw_spin_lock) from [] (get_table+0x14/0x5c [6lowpan]) [ 132.445922] [] (get_table [6lowpan]) from [] (lowpan_context_dbgfs_write+0x128/0x4ec [6lowpan]) [ 132.456860] [] (lowpan_context_dbgfs_write [6lowpan]) from [] (__vfs_write+0x20/0xd8) [ 132.466884] [] (__vfs_write) from [] (vfs_write+0x90/0x164) [ 132.474540] [] (vfs_write) from [] (SyS_write+0x44/0x9c) [ 132.481931] [] (SyS_write) from [] (ret_fast_syscall+0x0/0x54) You should see the same by enable "CONFIG_PROVE_LOCKING". I think it's because "spin_lock(&module_lock);" inside of "get_table" function. This is called by lowpan_xmit which has a softirq context (I think the experts says here bh (?bottom half?) are disabled). Anyway, you need to call spin_lock_bh/spin_unlock_bh. Linux device drivers says something similar: "Finally, spin_lock_bh disables software interrupts before taking the lock, but leaves hardware interrupts enabled." Without bh software interrupts are still enabled. > Signed-off-by: Lukasz Duda > Signed-off-by: Glenn Ruben Bakke > --- > include/net/6lowpan.h | 35 ++++ > net/6lowpan/Makefile | 2 +- > net/6lowpan/context.c | 551 ++++++++++++++++++++++++++++++++++++++++++++++++++ > net/6lowpan/context.h | 7 + > 4 files changed, 594 insertions(+), 1 deletion(-) > create mode 100644 net/6lowpan/context.c > create mode 100644 net/6lowpan/context.h > > diff --git a/include/net/6lowpan.h b/include/net/6lowpan.h > index 37ddbdf..ee3a455 100644 > --- a/include/net/6lowpan.h > +++ b/include/net/6lowpan.h > @@ -199,6 +199,27 @@ > > extern struct dentry *lowpan_debugfs; > > +struct lowpan_context_table { > + struct list_head list; > + > + /* Context entries */ > + struct net_device *netdev; > + struct list_head context_entries; > + atomic_t context_count; > +}; > + > +struct lowpan_context_entry { > + struct list_head list; > + struct rcu_head rcu; > + struct lowpan_context_table *ctx_table; > + > + /* Context parameters */ > + u8 cid; > + struct in6_addr prefix; > + unsigned int prefix_len; > + bool compression_flag; > +}; > + Is a list really necessary here? I assume that a context-id (one byte long) with a maximum value of 255. And then it's splitted into sci and dci, so we have a maximum of 16 and you already introduced nicely an LOWPAN_CONTEXT_TABLE_SIZE for that. Can't we simple to some array to have a fast lookup for lowpan_context_table[cid] and if it's not null then we have an entry for that? To lookup the CID by an ipv6 address, then we need to iterate the array and using ipv6_prefix_equal. > #ifdef DEBUG > /* print data in line */ > static inline void raw_dump_inline(const char *caller, char *msg, > @@ -337,6 +358,9 @@ lowpan_uncompress_size(const struct sk_buff *skb, u16 *dgram_offset) > if (!(iphc0 & 0x03)) > ret++; > > + if (iphc1 & LOWPAN_IPHC_CID) > + ret++; > + > ret += lowpan_addr_mode_size((iphc1 & LOWPAN_IPHC_SAM) >> > LOWPAN_IPHC_SAM_BIT); > > @@ -374,6 +398,17 @@ lowpan_uncompress_size(const struct sk_buff *skb, u16 *dgram_offset) > return skb->len + uncomp_header - ret; > } > > +int lowpan_context_table_alloc(struct net_device *netdev); > +int lowpan_context_table_free(struct net_device *netdev); > +int lowpan_context_free_all(void); > +int lowpan_context_add(struct net_device *netdev, > + struct lowpan_context_entry *entry); > +int lowpan_context_remove(struct lowpan_context_entry *entry); > +struct lowpan_context_entry * > +lowpan_context_decompress(struct net_device *netdev, u8 cid); > +struct lowpan_context_entry * > +lowpan_context_compress(struct net_device *netdev, struct in6_addr *addr); > + > int > lowpan_header_decompress(struct sk_buff *skb, struct net_device *dev, > const u8 *saddr, const u8 saddr_type, > diff --git a/net/6lowpan/Makefile b/net/6lowpan/Makefile > index eb8baa7..bda5be0 100644 > --- a/net/6lowpan/Makefile > +++ b/net/6lowpan/Makefile > @@ -1,6 +1,6 @@ > obj-$(CONFIG_6LOWPAN) += 6lowpan.o > > -6lowpan-y := iphc.o nhc.o > +6lowpan-y := iphc.o nhc.o context.o > > #rfc6282 nhcs > obj-$(CONFIG_6LOWPAN_NHC_DEST) += nhc_dest.o > diff --git a/net/6lowpan/context.c b/net/6lowpan/context.c > new file mode 100644 > index 0000000..00cd5af > --- /dev/null > +++ b/net/6lowpan/context.c > @@ -0,0 +1,551 @@ > +/* > + * Copyright (c) 2015 Nordic Semiconductor. All Rights Reserved. > + * > + * This program is free software; you can redistribute it and/or modify > + * it under the terms of the GNU General Public License version 2 and > + * only version 2 as published by the Free Software Foundation. > + * > + * This program is distributed in the hope that it will be useful, > + * but WITHOUT ANY WARRANTY; without even the implied warranty of > + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the > + * GNU General Public License for more details. > + */ > + > +#include > +#include > +#include > +#include > +#include > +#include > + > +#include > +#include > +#include > + > +#define LOWPAN_DBG(fmt, ...) pr_debug(fmt "\n", ##__VA_ARGS__) > + > +#define LOWPAN_CONTEXT_TABLE_SIZE 16 > +#define LOWPAN_CONTEXT_COMMAND_ADD "add" > +#define LOWPAN_CONTEXT_COMMAND_REMOVE "remove" > + > +#define CHECK_CID_RANGE(cid) ((cid) > 0 && (cid) < LOWPAN_CONTEXT_TABLE_SIZE) > +#define CHECK_PREFIX_RANGE(len) ((len) > 0 && (len) <= 128) > + > +static struct dentry *lowpan_context_debugfs; > + > +static LIST_HEAD(context_tables); > +static DEFINE_SPINLOCK(module_lock); > + > +static inline void entry_update(struct lowpan_context_entry *entry, please add lowpan prefix here to this function. > + u8 cid, > + struct in6_addr prefix, > + unsigned int prefix_len, > + bool compression_flag) > +{ > + /* Fill context entry. */ > + entry->cid = cid; > + entry->compression_flag = compression_flag; > + entry->prefix = prefix; > + entry->prefix_len = prefix_len; > +} > + > +static inline void entry_free(struct lowpan_context_entry *entry) lowpan prefix. > +{ > + /* Increase number of available contexts. */ > + atomic_dec(&entry->ctx_table->context_count); > + > + list_del_rcu(&entry->list); > + kfree_rcu(entry, rcu); > +} > + > +static int entry_add(struct lowpan_context_table *ctx_table, lowpan prefix. > + u8 cid, > + struct in6_addr prefix, > + unsigned int prefix_len, > + bool compression_flag) > +{ > + struct lowpan_context_entry *new_entry = NULL; > + > + new_entry = kzalloc(sizeof(*new_entry), GFP_ATOMIC); > + if (!new_entry) > + return -ENOMEM; > + > + /* Fill context entry. */ > + new_entry->ctx_table = ctx_table; > + entry_update(new_entry, cid, prefix, prefix_len, compression_flag); > + > + INIT_LIST_HEAD(&new_entry->list); > + list_add_rcu(&new_entry->list, &ctx_table->context_entries); > + > + /* Increase number of available contexts. */ > + atomic_inc(&ctx_table->context_count); > + > + return 0; > +} > + > +static void table_free(struct lowpan_context_table *ctx_table) lowpan prefix. > +{ > + struct lowpan_context_entry *entry = NULL; > + > + rcu_read_lock(); > + > + /* Clear context table. */ > + if (atomic_read(&ctx_table->context_count)) { > + list_for_each_entry_rcu(entry, > + &ctx_table->context_entries, > + list) > + entry_free(entry); > + } > + > + rcu_read_unlock(); > + > + /* Remove context table. */ > + list_del(&ctx_table->list); > + kfree(ctx_table); > +} > + > +static inline struct net_device *find_netdev(const char *name) lowpan prefix. > +{ > + struct net_device *netdev; > + > + rcu_read_lock(); > + netdev = dev_get_by_name_rcu(&init_net, name); > + rcu_read_unlock(); > + > + return netdev; > +} > + > +static struct lowpan_context_table *get_table(struct net_device *netdev) > +{ > + struct lowpan_context_table *entry; > + struct lowpan_context_table *net_table = NULL; > + > + spin_lock(&module_lock); > + > + list_for_each_entry(entry, &context_tables, list) { > + if (entry->netdev == netdev) { > + /* Table has been found. */ > + net_table = entry; > + break; > + } > + } > + > + spin_unlock(&module_lock); > + I know why you need such functionality. This is okay for now. But I already thought about a nicer handling for that (which is also useful for other mechanism). The idea is: The netdev structure has some private pointer "netdev->priv". Currently bluetooth 6lowpan/802.15.4 6lowpan do their own stuff inside this struct which is okay. But we should provide some "upper class" struct for all ARPHRD_6LOWPAN, which looks like: ----------------------------- | 6LOWPAN_ARPHRD_STRUCT | <-- All ARPHRD_6LOWPAN have this struct as first ----------------------------- | PRIVATE_DATA | <-- 802.15.4/btle own stuff (private struct of subsystem) simple a | | "u8 priv __aligned(sizeof(void *));" inside ARPHRD_6LOWPAN which need to be at last ----------------------------- Then you can put the net_table into the "6LOWPAN_ARPHRD_STRUCT" and cast the "netdev->priv" pointer to "6LOWPAN_ARPHRD_STRUCT". We really need such thing to avoid the above search&found functionality. We should introduce such behaviour at first, then you can rebase your stuff on it. Also we need some functionality lowpan_alloc_netdev which ensure the priv size is "sizeof(6LOWPAN_ARPHRD_STRUCT) + sizeof(PRIVATE_DATA)". In upper layers like IPv6 you can do the following then: if (dev->type == ARPHRD_6LOWPAN) { 6LOWPAN_ARPHRD_STRUCT foobar = (struct 6LOWPAN_ARPHRD_STRUCT *)dev->priv; ...do great cid handling here... } I hope this will also help you by implementing 6CO. btw: (struct 6LOWPAN_ARPHRD_STRUCT *) should be implemented by a macro. So please begin at first to add such functionality, please. Is that okay for you? > + return net_table; > +} > + > +static struct lowpan_context_entry * > +get_ctx_by_cid(struct lowpan_context_table *table, u8 cid) > +{ > + struct lowpan_context_entry *entry; > + struct lowpan_context_entry *context = NULL; > + > + rcu_read_lock(); > + > + list_for_each_entry_rcu(entry, &table->context_entries, list) { > + if (entry->cid == cid) { > + /* Context entry has been found. */ > + context = entry; > + break; > + } > + } > + > + rcu_read_unlock(); > + > + return context; > +} > + > +static struct lowpan_context_entry * > +get_ctx_by_addr(struct lowpan_context_table *table, struct in6_addr *addr) > +{ > + struct lowpan_context_entry *entry; > + struct lowpan_context_entry *best_match = NULL; > + unsigned int compare_len; > + > + rcu_read_lock(); > + > + list_for_each_entry_rcu(entry, &table->context_entries, list) { > + if (!entry->compression_flag) > + continue; > + > + compare_len = entry->prefix_len >= 64 ? entry->prefix_len : 64; > + if (ipv6_prefix_equal(addr, &entry->prefix, compare_len)) { > + /* Valid context entry has been found. Check if prefix > + * can cover more bytes than previous one. > + */ > + if (!best_match || > + (best_match->prefix_len < entry->prefix_len)) > + best_match = entry; > + } > + } > + > + rcu_read_unlock(); > + > + return best_match; > +} > + > +ssize_t lowpan_context_dbgfs_write(struct file *fp, > + const char __user *user_buffer, > + size_t count, > + loff_t *position) > +{ > + char buf[128]; > + char str_operation[16]; > + char str_interface[16]; > + char str_ipv6addr[40]; > + size_t buf_size = min(count, sizeof(buf) - 1); > + int n; > + int ret; > + u8 cid; > + unsigned int prefix_length; > + unsigned int c_flag; > + struct in6_addr ctx_prefix; > + struct net_device *netdev; > + struct lowpan_context_table *ctx_table; > + struct lowpan_context_entry *entry; > + > + memset(&ctx_prefix, 0, sizeof(ctx_prefix)); > + > + if (copy_from_user(buf, user_buffer, buf_size)) > + return -EFAULT; > + > + buf[buf_size] = '\0'; > + > + /* Parse input parameters. */ > + n = sscanf(buf, "%s %s %hhd %s %d %d", > + str_operation, str_interface, &cid, str_ipv6addr, > + &prefix_length, &c_flag); > + > + netdev = find_netdev(str_interface); > + /* Look up for net device. */ > + if (!netdev) { > + LOWPAN_DBG("Cannot find given interface"); > + return -EINVAL; > + } > + > + if (!CHECK_CID_RANGE(cid)) { > + LOWPAN_DBG("CID value is out of range"); > + return -EINVAL; > + } > + > + /* Get context table. */ > + ctx_table = get_table(netdev); > + > + if (!ctx_table) { > + LOWPAN_DBG("Cannot find context table for %s interface", > + str_interface); > + return -EINVAL; > + } > + > + entry = get_ctx_by_cid(ctx_table, cid); > + > + /* Execute command. */ > + if (!memcmp(str_operation, LOWPAN_CONTEXT_COMMAND_ADD, > + sizeof(LOWPAN_CONTEXT_COMMAND_ADD))) { > + /* Parse IPv6 address. */ > + in6_pton(str_ipv6addr, > + sizeof(str_ipv6addr), > + ctx_prefix.s6_addr, > + '\0', > + NULL); > + > + /* Check parameters. */ > + if (ipv6_addr_any(&ctx_prefix) || > + !CHECK_PREFIX_RANGE(prefix_length)) { > + LOWPAN_DBG("Given parameters are not valid"); > + return -EINVAL; > + } > + > + LOWPAN_DBG("Got request: I:%s CID:%d Prefix:%pI6c/%d C:%d", > + str_interface, cid, &ctx_prefix, prefix_length, > + !!c_flag); > + > + /* Check if entry for given CID already exists. */ > + if (entry) { > + /* Just update parameters. */ > + rcu_read_lock(); > + entry_update(entry, cid, ctx_prefix, prefix_length, > + !!c_flag); > + rcu_read_unlock(); > + } else { > + /* Create a new entry. */ > + ret = entry_add(ctx_table, cid, ctx_prefix, > + prefix_length, !!c_flag); > + if (ret < 0) { > + LOWPAN_DBG("Cannot add context entry"); > + return ret; > + } > + } > + } else if (memcmp(str_operation, LOWPAN_CONTEXT_COMMAND_REMOVE, > + sizeof(LOWPAN_CONTEXT_COMMAND_REMOVE)) == 0) { > + LOWPAN_DBG("Got new remove request: I:%s CID:%d", > + str_interface, cid); > + > + if (!entry) { > + LOWPAN_DBG("Cannot find context entry"); > + return -EINVAL; > + } > + > + rcu_read_lock(); > + entry_free(entry); > + rcu_read_unlock(); > + } else { > + LOWPAN_DBG("Invalid command - Cannot process the request"); > + return -EINVAL; > + } > + > + return count; > +} > + > +static int lowpan_context_show(struct seq_file *f, void *ptr) > +{ > + struct lowpan_context_table *table; > + struct lowpan_context_entry *entry; > + > + list_for_each_entry(table, &context_tables, list) { > + if (!atomic_read(&table->context_count)) > + break; > + > + seq_printf(f, "Context table of interface %s\r\n\r\n", > + table->netdev->name); > + seq_printf(f, "%-3s %-39s %-3s %-3s \r\n", > + "CID", "Prefix", "Len", "CF"); > + > + list_for_each_entry_rcu(entry, &table->context_entries, list) > + seq_printf(f, "%-3d %-39pI6c %-3d %-3s \r\n", > + entry->cid, > + &entry->prefix, > + entry->prefix_len, > + entry->compression_flag ? "1" : "0"); > + seq_puts(f, "\r\n\r\n"); > + } > + > + return 0; > +} > + > +int lowpan_context_dbgfs_open(struct inode *inode, struct file *file) > +{ > + return single_open(file, lowpan_context_show, inode->i_private); > +} > + > +int lowpan_context_table_alloc(struct net_device *netdev) > +{ > + struct lowpan_context_table *ctx_table = NULL; > + > + if (!netdev) { > + LOWPAN_DBG("Network device has to be specified"); > + return -EPERM; > + } > + > + /* Look for context table. */ > + ctx_table = get_table(netdev); > + > + if (ctx_table) { > + LOWPAN_DBG("Context table already exists for interface %s %p", > + netdev->name, ctx_table); > + return -EEXIST; > + } > + > + ctx_table = kzalloc(sizeof(*ctx_table), GFP_ATOMIC); > + if (!ctx_table) > + return -ENOMEM; > + > + /* Assign network device to context table. */ > + ctx_table->netdev = netdev; > + > + /* Initialize contexts list. */ > + INIT_LIST_HEAD(&ctx_table->context_entries); > + > + spin_lock(&module_lock); > + INIT_LIST_HEAD(&ctx_table->list); > + list_add_rcu(&ctx_table->list, &context_tables); > + spin_unlock(&module_lock); > + > + return 0; > +} > +EXPORT_SYMBOL_GPL(lowpan_context_table_alloc); > + > +int lowpan_context_table_free(struct net_device *netdev) > +{ > + struct lowpan_context_table *ctx_table = NULL; > + > + if (!netdev) { > + LOWPAN_DBG("Network device has to be specified"); > + return -EPERM; > + } > + > + /* Look for context table. */ > + ctx_table = get_table(netdev); > + if (!ctx_table) { > + LOWPAN_DBG("Cannot find context table for interface %s", > + netdev->name); > + return -ENOENT; > + } > + > + spin_lock(&module_lock); > + table_free(ctx_table); > + spin_unlock(&module_lock); > + > + return 0; > +} > +EXPORT_SYMBOL_GPL(lowpan_context_table_free); > + > +int lowpan_context_add(struct net_device *netdev, > + struct lowpan_context_entry *entry) > +{ > + int ret; > + struct lowpan_context_table *ctx_table = NULL; > + struct lowpan_context_entry *stored_entry = NULL; > + > + if (!entry || !netdev) { > + LOWPAN_DBG("Parameters are incorrect"); > + return -EPERM; > + } > + > + /* Get context table. */ > + ctx_table = get_table(netdev); > + if (!ctx_table) { > + LOWPAN_DBG("Cannot find context table for %s interface", > + netdev->name); > + return -EINVAL; > + } > + > + stored_entry = get_ctx_by_cid(ctx_table, entry->cid); > + > + /* Check if entry for given CID already exists. */ > + if (entry) { > + /* Just update parameters. */ > + rcu_read_lock(); > + entry_update(stored_entry, entry->cid, entry->prefix, > + entry->prefix_len, entry->compression_flag); > + rcu_read_unlock(); > + } else { > + /* Create a new entry. */ > + ret = entry_add(ctx_table, entry->cid, entry->prefix, > + entry->prefix_len, entry->compression_flag); > + > + if (ret < 0) { > + LOWPAN_DBG("Cannot add context entry"); > + return ret; > + } > + } > + > + return 0; > +} > +EXPORT_SYMBOL_GPL(lowpan_context_add); > + Don't export function which isn't used by other modules. Maybe you prepared for using this function for the 6CO field in ipv6. If yes, we can do that later. > +int lowpan_context_remove(struct lowpan_context_entry *entry) > +{ > + if (!entry) { > + LOWPAN_DBG("Given entry is NULL"); > + return -EPERM; > + } > + > + /* Free given entry. */ > + rcu_read_lock(); > + entry_free(entry); > + rcu_read_unlock(); > + > + return 0; > +} > +EXPORT_SYMBOL_GPL(lowpan_context_remove); > + same here. > +struct lowpan_context_entry * > +lowpan_context_decompress(struct net_device *netdev, u8 cid) > +{ > + struct lowpan_context_table *ctx_table = NULL; > + struct lowpan_context_entry *entry = NULL; > + > + if (!netdev) { > + LOWPAN_DBG("Network device has to be specified"); > + return NULL; > + } > + > + /* Get proper interface table. */ > + ctx_table = get_table(netdev); > + if (!ctx_table) { > + LOWPAN_DBG("Cannot find context table for interface %s", > + netdev->name); > + return NULL; > + } > + > + /* Search for given CID. */ > + entry = get_ctx_by_cid(ctx_table, cid); > + if (!entry) { > + LOWPAN_DBG("There is no context of id:%d for interface %s", > + cid, netdev->name); > + return NULL; > + } > + > + LOWPAN_DBG("Found context prefix for context of id:%d - %pI6c", > + entry->cid, &entry->prefix); > + > + return entry; > +} > +EXPORT_SYMBOL_GPL(lowpan_context_decompress); > + same here. > +struct lowpan_context_entry *lowpan_context_compress(struct net_device *netdev, > + struct in6_addr *addr) > +{ > + struct lowpan_context_table *ctx_table = NULL; > + struct lowpan_context_entry *entry = NULL; > + > + if (!netdev || !addr) { > + LOWPAN_DBG("Network device and address has to be specified"); > + return NULL; > + } > + > + /* Get proper interface table. */ > + ctx_table = get_table(netdev); > + if (!ctx_table) { > + LOWPAN_DBG("Cannot find context table for interface %s", > + netdev->name); > + return NULL; > + } > + > + /* Search for given address. */ > + entry = get_ctx_by_addr(ctx_table, addr); > + if (!entry) { > + LOWPAN_DBG("No context for address %pI6c for interface %s", > + addr, netdev->name); > + return NULL; > + } > + > + LOWPAN_DBG("Found context of id:%d", entry->cid); > + > + /* Return null in case no compression capability in found context */ > + return entry; > +} > +EXPORT_SYMBOL_GPL(lowpan_context_compress); > + same here. > +const struct file_operations lowpan_context_fops = { > + .open = lowpan_context_dbgfs_open, > + .read = seq_read, > + .write = lowpan_context_dbgfs_write, > + .llseek = seq_lseek, > + .release = single_release > +}; > + > +void lowpan_context_init(void) > +{ > + lowpan_context_debugfs = debugfs_create_file("context", 0664, > + lowpan_debugfs, NULL, > + &lowpan_context_fops); > +} > +EXPORT_SYMBOL_GPL(lowpan_context_init); > + same here. > +void lowpan_context_uninit(void) > +{ > + struct lowpan_context_table *entry = NULL; > + > + spin_lock(&module_lock); > + > + list_for_each_entry(entry, &context_tables, list) > + table_free(entry); > + > + spin_unlock(&module_lock); > + > + debugfs_remove(lowpan_context_debugfs); > +} > +EXPORT_SYMBOL_GPL(lowpan_context_uninit); same here. > diff --git a/net/6lowpan/context.h b/net/6lowpan/context.h > new file mode 100644 > index 0000000..88303b5 > --- /dev/null > +++ b/net/6lowpan/context.h > @@ -0,0 +1,7 @@ > +#ifndef __6LOWPAN_CONTEXT_H > +#define __6LOWPAN_CONTEXT_H > + > +void lowpan_context_init(void); > +void lowpan_context_uninit(void); > + > +#endif /* __6LOWPAN_CONTEXT_H */ > -- > 2.1.4 >