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author | Sebastian Andrzej Siewior <bigeasy@linutronix.de> | 2013-03-20 18:06:20 +0100 |
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committer | Sebastian Andrzej Siewior <bigeasy@linutronix.de> | 2016-02-13 00:36:32 +0100 |
commit | fb85b8544939d8e2d9fda30cfd69f8d3cad21b7b (patch) | |
tree | 953bc562799c12482104b59b8ec9874a5607a350 | |
parent | 228ae84068bf25aea05e1e0a9405e8ebfcf88786 (diff) | |
download | rt-linux-fb85b8544939d8e2d9fda30cfd69f8d3cad21b7b.tar.gz |
net: Add a mutex around devnet_rename_seq
On RT write_seqcount_begin() disables preemption and device_rename()
allocates memory with GFP_KERNEL and grabs later the sysfs_mutex
mutex. Serialize with a mutex and add use the non preemption disabling
__write_seqcount_begin().
To avoid writer starvation, let the reader grab the mutex and release
it when it detects a writer in progress. This keeps the normal case
(no reader on the fly) fast.
[ tglx: Instead of replacing the seqcount by a mutex, add the mutex ]
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
-rw-r--r-- | net/core/dev.c | 34 |
1 files changed, 20 insertions, 14 deletions
diff --git a/net/core/dev.c b/net/core/dev.c index caa8303cac0c1..c82f163fc1742 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -186,6 +186,7 @@ static unsigned int napi_gen_id; static DEFINE_HASHTABLE(napi_hash, 8); static seqcount_t devnet_rename_seq; +static DEFINE_MUTEX(devnet_rename_mutex); static inline void dev_base_seq_inc(struct net *net) { @@ -884,7 +885,8 @@ retry: strcpy(name, dev->name); rcu_read_unlock(); if (read_seqcount_retry(&devnet_rename_seq, seq)) { - cond_resched(); + mutex_lock(&devnet_rename_mutex); + mutex_unlock(&devnet_rename_mutex); goto retry; } @@ -1153,20 +1155,17 @@ int dev_change_name(struct net_device *dev, const char *newname) if (dev->flags & IFF_UP) return -EBUSY; - write_seqcount_begin(&devnet_rename_seq); + mutex_lock(&devnet_rename_mutex); + __raw_write_seqcount_begin(&devnet_rename_seq); - if (strncmp(newname, dev->name, IFNAMSIZ) == 0) { - write_seqcount_end(&devnet_rename_seq); - return 0; - } + if (strncmp(newname, dev->name, IFNAMSIZ) == 0) + goto outunlock; memcpy(oldname, dev->name, IFNAMSIZ); err = dev_get_valid_name(net, dev, newname); - if (err < 0) { - write_seqcount_end(&devnet_rename_seq); - return err; - } + if (err < 0) + goto outunlock; if (oldname[0] && !strchr(oldname, '%')) netdev_info(dev, "renamed from %s\n", oldname); @@ -1179,11 +1178,12 @@ rollback: if (ret) { memcpy(dev->name, oldname, IFNAMSIZ); dev->name_assign_type = old_assign_type; - write_seqcount_end(&devnet_rename_seq); - return ret; + err = ret; + goto outunlock; } - write_seqcount_end(&devnet_rename_seq); + __raw_write_seqcount_end(&devnet_rename_seq); + mutex_unlock(&devnet_rename_mutex); netdev_adjacent_rename_links(dev, oldname); @@ -1204,7 +1204,8 @@ rollback: /* err >= 0 after dev_alloc_name() or stores the first errno */ if (err >= 0) { err = ret; - write_seqcount_begin(&devnet_rename_seq); + mutex_lock(&devnet_rename_mutex); + __raw_write_seqcount_begin(&devnet_rename_seq); memcpy(dev->name, oldname, IFNAMSIZ); memcpy(oldname, newname, IFNAMSIZ); dev->name_assign_type = old_assign_type; @@ -1217,6 +1218,11 @@ rollback: } return err; + +outunlock: + __raw_write_seqcount_end(&devnet_rename_seq); + mutex_unlock(&devnet_rename_mutex); + return err; } /** |