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Diffstat (limited to 'ufs/pager.c')
-rw-r--r--ufs/pager.c105
1 files changed, 65 insertions, 40 deletions
diff --git a/ufs/pager.c b/ufs/pager.c
index 3038932d..1e3d140c 100644
--- a/ufs/pager.c
+++ b/ufs/pager.c
@@ -21,9 +21,9 @@
#include <unistd.h>
#include <hurd/store.h>
-spin_lock_t node2pagelock = SPIN_LOCK_INITIALIZER;
+pthread_spinlock_t node2pagelock = PTHREAD_SPINLOCK_INITIALIZER;
-spin_lock_t unlocked_pagein_lock = SPIN_LOCK_INITIALIZER;
+pthread_spinlock_t unlocked_pagein_lock = PTHREAD_SPINLOCK_INITIALIZER;
#ifdef DONT_CACHE_MEMORY_OBJECTS
#define MAY_CACHE 0
@@ -47,11 +47,11 @@ find_address (struct user_pager_info *upi,
vm_address_t offset,
daddr_t *addr,
int *disksize,
- struct rwlock **nplock,
+ pthread_rwlock_t **nplock,
int isread)
{
error_t err;
- struct rwlock *lock;
+ pthread_rwlock_t *lock;
assert (upi->type == DISK || upi->type == FILE_DATA);
@@ -81,37 +81,49 @@ find_address (struct user_pager_info *upi,
I think this is sufficiently rare to put it off for the time
being.) */
- spin_lock (&unlocked_pagein_lock);
+ pthread_spin_lock (&unlocked_pagein_lock);
if (offset >= upi->allow_unlocked_pagein
&& (offset + vm_page_size
<= upi->allow_unlocked_pagein + upi->unlocked_pagein_length))
{
- spin_unlock (&unlocked_pagein_lock);
+ pthread_spin_unlock (&unlocked_pagein_lock);
*nplock = 0;
goto have_lock;
}
- spin_unlock (&unlocked_pagein_lock);
+ pthread_spin_unlock (&unlocked_pagein_lock);
/* Block on the rwlock if necessary; but when we wake up,
don't acquire it; check again from the top.
This is mutated inline from rwlock.h. */
lock = &np->dn->allocptrlock;
- mutex_lock (&lock->master);
- if (lock->readers == -1 || lock->writers_waiting)
+ /*
+ TD - Why do we lock first?
+ To prevent this nigh-impossible scenario:
+ 1) trylock - writer has lock
+ 2) switch back to writer before we lock waitlock
+ 3) writer finishes: releases lock and broadcasts
+ 4) we wait for a condition that will never get broadcast
+ With this, either we get the lock, or we get the signal.
+ */
+ pthread_mutex_lock (&np->dn->waitlock);
+ if (pthread_rwlock_tryrdlock (lock))
{
- lock->readers_waiting++;
- condition_wait (&lock->wakeup, &lock->master);
- lock->readers_waiting--;
- mutex_unlock (&lock->master);
+ /*
+ TD - we now don't block on the rwlock. Instead, we wait on a
+ condition that will be signalled when the lock is unlocked,
+ or when it is safe not to lock the page. We don't spin on an
+ invariant, as spurius wakeups can do no harm.
+ */
+ pthread_cond_wait (&np->dn->waitcond, &np->dn->waitlock);
+ pthread_mutex_unlock (&np->dn->waitlock);
goto try_again;
}
- lock->readers++;
- mutex_unlock (&lock->master);
+ pthread_mutex_unlock (&np->dn->waitlock);
*nplock = lock;
}
else
{
- rwlock_reader_lock (&np->dn->allocptrlock);
+ pthread_rwlock_rdlock (&np->dn->allocptrlock);
*nplock = &np->dn->allocptrlock;
}
@@ -120,7 +132,7 @@ find_address (struct user_pager_info *upi,
if (offset >= np->allocsize)
{
if (*nplock)
- rwlock_reader_unlock (*nplock);
+ pthread_rwlock_unlock (*nplock);
if (isread)
return EIO;
else
@@ -138,7 +150,7 @@ find_address (struct user_pager_info *upi,
err = fetch_indir_spec (np, lblkno (sblock, offset), indirs);
if (err && *nplock)
- rwlock_reader_unlock (*nplock);
+ pthread_rwlock_unlock (*nplock);
else
{
if (indirs[0].bno)
@@ -162,7 +174,7 @@ pager_read_page (struct user_pager_info *pager,
int *writelock)
{
error_t err;
- struct rwlock *nplock;
+ pthread_rwlock_t *nplock;
daddr_t addr;
int disksize;
@@ -193,7 +205,7 @@ pager_read_page (struct user_pager_info *pager,
}
if (nplock)
- rwlock_reader_unlock (nplock);
+ pthread_rwlock_unlock (nplock);
return err;
}
@@ -207,7 +219,7 @@ pager_write_page (struct user_pager_info *pager,
{
daddr_t addr;
int disksize;
- struct rwlock *nplock;
+ pthread_rwlock_t *nplock;
error_t err;
err = find_address (pager, page, &addr, &disksize, &nplock, 0);
@@ -226,7 +238,7 @@ pager_write_page (struct user_pager_info *pager,
err = 0;
if (nplock)
- rwlock_reader_unlock (nplock);
+ pthread_rwlock_unlock (nplock);
return err;
}
@@ -268,7 +280,7 @@ pager_unlock_page (struct user_pager_info *pager,
dn = np->dn;
di = dino (dn->number);
- rwlock_writer_lock (&dn->allocptrlock);
+ pthread_rwlock_wrlock (&dn->allocptrlock);
/* If this is the last block, we don't let it get unlocked. */
if (address + __vm_page_size
@@ -276,21 +288,31 @@ pager_unlock_page (struct user_pager_info *pager,
{
printf ("attempt to unlock at last block denied\n");
fflush (stdout);
- rwlock_writer_unlock (&dn->allocptrlock);
+ pthread_rwlock_unlock (&dn->allocptrlock);
+ /* Wake up any remaining sleeping readers. Wow, so much work.... */
+ pthread_mutex_lock (&dn->waitlock);
+ pthread_cond_broadcast (&dn->waitcond);
+ pthread_mutex_unlock (&dn->waitlock);
return EIO;
}
err = fetch_indir_spec (np, lblkno (sblock, address), indirs);
if (err)
{
- rwlock_writer_unlock (&dn->allocptrlock);
+ pthread_rwlock_unlock (&dn->allocptrlock);
+ pthread_mutex_lock (&dn->waitlock);
+ pthread_cond_broadcast (&dn->waitcond);
+ pthread_mutex_unlock (&dn->waitlock);
return EIO;
}
err = diskfs_catch_exception ();
if (err)
{
- rwlock_writer_unlock (&dn->allocptrlock);
+ pthread_rwlock_unlock (&dn->allocptrlock);
+ pthread_mutex_lock (&dn->waitlock);
+ pthread_cond_broadcast (&dn->waitcond);
+ pthread_mutex_unlock (&dn->waitlock);
return EIO;
}
@@ -421,7 +443,10 @@ pager_unlock_page (struct user_pager_info *pager,
out:
diskfs_end_catch_exception ();
- rwlock_writer_unlock (&dn->allocptrlock);
+ pthread_rwlock_unlock (&dn->allocptrlock);
+ pthread_mutex_lock (&dn->waitlock);
+ pthread_cond_broadcast (&dn->waitcond);
+ pthread_mutex_unlock (&dn->waitlock);
return err;
}
@@ -452,10 +477,10 @@ pager_clear_user_data (struct user_pager_info *upi)
/* XXX Do the right thing for the disk pager here too. */
if (upi->type == FILE_DATA)
{
- spin_lock (&node2pagelock);
+ pthread_spin_lock (&node2pagelock);
if (upi->np->dn->fileinfo == upi)
upi->np->dn->fileinfo = 0;
- spin_unlock (&node2pagelock);
+ pthread_spin_unlock (&node2pagelock);
diskfs_nrele_light (upi->np);
}
free (upi);
@@ -491,11 +516,11 @@ diskfs_file_update (struct node *np,
struct dirty_indir *d, *tmp;
struct user_pager_info *upi;
- spin_lock (&node2pagelock);
+ pthread_spin_lock (&node2pagelock);
upi = np->dn->fileinfo;
if (upi)
ports_port_ref (upi->p);
- spin_unlock (&node2pagelock);
+ pthread_spin_unlock (&node2pagelock);
if (upi)
{
@@ -522,11 +547,11 @@ flush_node_pager (struct node *node)
struct disknode *dn = node->dn;
struct dirty_indir *dirty = dn->dirty;
- spin_lock (&node2pagelock);
+ pthread_spin_lock (&node2pagelock);
upi = dn->fileinfo;
if (upi)
ports_port_ref (upi->p);
- spin_unlock (&node2pagelock);
+ pthread_spin_unlock (&node2pagelock);
if (upi)
{
@@ -558,7 +583,7 @@ diskfs_get_filemap (struct node *np, vm_prot_t prot)
&& (!direct_symlink_extension
|| np->dn_stat.st_size >= sblock->fs_maxsymlinklen)));
- spin_lock (&node2pagelock);
+ pthread_spin_lock (&node2pagelock);
do
if (!np->dn->fileinfo)
{
@@ -575,7 +600,7 @@ diskfs_get_filemap (struct node *np, vm_prot_t prot)
{
diskfs_nrele_light (np);
free (upi);
- spin_unlock (&node2pagelock);
+ pthread_spin_unlock (&node2pagelock);
return MACH_PORT_NULL;
}
np->dn->fileinfo = upi;
@@ -596,7 +621,7 @@ diskfs_get_filemap (struct node *np, vm_prot_t prot)
}
while (right == MACH_PORT_NULL);
- spin_unlock (&node2pagelock);
+ pthread_spin_unlock (&node2pagelock);
mach_port_insert_right (mach_task_self (), right, right,
MACH_MSG_TYPE_MAKE_SEND);
@@ -611,11 +636,11 @@ drop_pager_softrefs (struct node *np)
{
struct user_pager_info *upi;
- spin_lock (&node2pagelock);
+ pthread_spin_lock (&node2pagelock);
upi = np->dn->fileinfo;
if (upi)
ports_port_ref (upi->p);
- spin_unlock (&node2pagelock);
+ pthread_spin_unlock (&node2pagelock);
if (MAY_CACHE && upi)
pager_change_attributes (upi->p, 0, MEMORY_OBJECT_COPY_DELAY, 0);
@@ -630,11 +655,11 @@ allow_pager_softrefs (struct node *np)
{
struct user_pager_info *upi;
- spin_lock (&node2pagelock);
+ pthread_spin_lock (&node2pagelock);
upi = np->dn->fileinfo;
if (upi)
ports_port_ref (upi->p);
- spin_unlock (&node2pagelock);
+ pthread_spin_unlock (&node2pagelock);
if (MAY_CACHE && upi)
pager_change_attributes (upi->p, 1, MEMORY_OBJECT_COPY_DELAY, 0);
generated by cgit v1.2.3 (git 2.46.0) at 2025-02-23 03:39:36 +0000