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isdn.bkl-remove.ippp_lock.patch:
added ippp_lock to ippp_struct
* It appeared that the BKL was being used to guard the file struct's
private data field, which is a ippp_struct. I added a semaphore to
that structure which can be locked instead of the BKL.
I've been examining the continuing additions of the big kernel lock
(BKL) to the 2.5 tree. I noticed that in 2.5.3, the ISDN subsystem
added the BKL to several places. In response to this, I have written
several patches to attempt removal of the BKL from the ISDN subsystem.
I have little knowledge of the drivers themselves, so I would like some
assistance from those of you who understand them better. I probably
have an over-simplified view of the code, so my patches may be too
simplistic.
--
Dave Hansen
haveblue@us.ibm.com
--- linux-2.5.3-clean/drivers/isdn/isdn_ppp.c Fri Feb 1 16:43:35 2002
+++ linux/drivers/isdn/isdn_ppp.c Mon Feb 4 11:34:16 2002
@@ -329,7 +329,7 @@
int i;
struct ippp_struct *is;
- lock_kernel();
+ down( ((ippp_struct*)file->private_data)->ippp_lock);
is = file->private_data;
@@ -385,7 +385,7 @@
isdn_unlock_drivers();
- unlock_kernel();
+ up(&is->ippp_lock)
return 0;
}
@@ -588,7 +588,7 @@
unsigned long flags;
struct ippp_struct *is;
- lock_kernel();
+ down( ((ippp_struct*)file->private_data)->ippp_lock);
is = file->private_data;
if (is->debug & 0x2)
@@ -624,7 +624,7 @@
restore_flags(flags);
out:
- unlock_kernel();
+ up(&is->ippp_lock);
return mask;
}
@@ -702,7 +702,7 @@
if (off != &file->f_pos)
return -ESPIPE;
- lock_kernel();
+ down( ((ippp_struct*)file->private_data)->ippp_lock);
is = file->private_data;
@@ -737,7 +737,7 @@
retval = count;
out:
- unlock_kernel();
+ up(&is->ippp_lock);
return retval;
}
@@ -757,7 +757,7 @@
if (off != &file->f_pos)
return -ESPIPE;
- lock_kernel();
+ down( ((ippp_struct*)file->private_data)->ippp_lock);
is = file->private_data;
@@ -826,7 +826,7 @@
retval = count;
out:
- unlock_kernel();
+ up(&is->ippp_lock);
return retval;
}
--- linux-2.5.3-clean/drivers/isdn/isdn_ppp.c Wed Feb 6 11:42:18 2002
+++ linux/drivers/isdn/isdn_ppp.c Wed Feb 6 11:05:41 2002
@@ -866,6 +866,7 @@
return -1;
}
memset((char *) ippp_table[i], 0, sizeof(struct ippp_struct));
+ init_MUTEX(&ippp_table[i]->ippp_lock);
ippp_table[i]->state = 0;
ippp_table[i]->first = ippp_table[i]->rq + NUM_RCV_BUFFS - 1;
ippp_table[i]->last = ippp_table[i]->rq;
--- linux-2.5.3-clean/include/linux/isdn_ppp.h Sun Sep 30 12:26:42 2001
+++ linux/include/linux/isdn_ppp.h Mon Feb 4 11:34:16 2002
@@ -201,6 +201,7 @@
};
struct ippp_struct {
+ struct semaphore ippp_lock;
struct ippp_struct *next_link;
int state;
struct ippp_buf_queue rq[NUM_RCV_BUFFS]; /* packet queue for isdn_ppp_read() */
-
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This archive was generated by hypermail 2b29 : Thu Feb 07 2002 - 21:01:03 EST