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cifs: convert cifs_tcp_ses_lock from a rwlock to a spinlock

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cifs_tcp_ses_lock is a rwlock with protects the cifs_tcp_ses_list,
server->smb_ses_list and the ses->tcon_list. It also protects a few
ref counters in server, ses and tcon. In most cases the critical section
doesn't seem to be large, in a few cases where it is slightly large, there
seem to be really no benefit from concurrent access. I briefly considered RCU
mechanism but it appears to me that there is no real need.

Replace it with a spinlock and get rid of the last rwlock in the cifs code.

Signed-off-by: Suresh Jayaraman <sjayaraman@suse.de>
Signed-off-by: Steve French <sfrench@us.ibm.com>
This commit is contained in:
Suresh Jayaraman
2010-10-18 23:29:37 +05:30
committed by Steve French
parent 3e24e13287
commit 3f9bcca782
7 changed files with 58 additions and 58 deletions
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12
fs/cifs/cifs_debug.c
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@@ -148,7 +148,7 @@ static int cifs_debug_data_proc_show(struct seq_file *m, void *v)
seq_printf(m, "Servers:");
i = 0;
read_lock(&cifs_tcp_ses_lock);
spin_lock(&cifs_tcp_ses_lock);
list_for_each(tmp1, &cifs_tcp_ses_list) {
server = list_entry(tmp1, struct TCP_Server_Info,
tcp_ses_list);
@@ -230,7 +230,7 @@ static int cifs_debug_data_proc_show(struct seq_file *m, void *v)
spin_unlock(&GlobalMid_Lock);
}
}
read_unlock(&cifs_tcp_ses_lock);
spin_unlock(&cifs_tcp_ses_lock);
seq_putc(m, '\n');
/* BB add code to dump additional info such as TCP session info now */
@@ -270,7 +270,7 @@ static ssize_t cifs_stats_proc_write(struct file *file,
atomic_set(&totBufAllocCount, 0);
atomic_set(&totSmBufAllocCount, 0);
#endif /* CONFIG_CIFS_STATS2 */
read_lock(&cifs_tcp_ses_lock);
spin_lock(&cifs_tcp_ses_lock);
list_for_each(tmp1, &cifs_tcp_ses_list) {
server = list_entry(tmp1, struct TCP_Server_Info,
tcp_ses_list);
@@ -303,7 +303,7 @@ static ssize_t cifs_stats_proc_write(struct file *file,
}
}
}
read_unlock(&cifs_tcp_ses_lock);
spin_unlock(&cifs_tcp_ses_lock);
}
return count;
@@ -343,7 +343,7 @@ static int cifs_stats_proc_show(struct seq_file *m, void *v)
GlobalCurrentXid, GlobalMaxActiveXid);
i = 0;
read_lock(&cifs_tcp_ses_lock);
spin_lock(&cifs_tcp_ses_lock);
list_for_each(tmp1, &cifs_tcp_ses_list) {
server = list_entry(tmp1, struct TCP_Server_Info,
tcp_ses_list);
@@ -397,7 +397,7 @@ static int cifs_stats_proc_show(struct seq_file *m, void *v)
}
}
}
read_unlock(&cifs_tcp_ses_lock);
spin_unlock(&cifs_tcp_ses_lock);
seq_putc(m, '\n');
return 0;