I've been using this patch for some time now; it fixes
a nasty oops in khttpd on smp, and adds crucial details to the doc.
Sure, khttpd is going away in 2.5, but 2.4 is stable, let's fix it there.
I sent it multiple times to the author of khttpd and to the khttpd-users
mailing list, and even to linux-kernel; I received good comments
from khttpd-users but silence elsewhere.
In desperation, I finally read the MAINTAINERS file, and learned that there
is no official maintainer for khttpd, so here I am mailing it to the
'mail patches to' address for General Networking Stuff.
Any chance this could be blessed for transmission to Marcello for 2.4.20?
Thanks,
Dan Kegel
diff -x '*times*' -x '.*' -x '*.o' -Naur linux-2.4.17-orig/net/khttpd/README
linux/net/khttpd/README
--- linux-2.4.17-orig/net/khttpd/README Thu Nov 16 14:07:53 2000
+++ linux/net/khttpd/README Mon May 27 22:43:43 2002
@@ -14,14 +14,15 @@
other webservers in that it runs from within the Linux-kernel as a module
(device-driver).
- kHTTPd handles only static (file based) web-pages, and passes all requests
- for non-static information to a regular userspace-webserver such as Apache
or
- Zeus. The userspace-daemon doesn't have to be altered in any way.
+ kHTTPd handles only static (file based) web-pages, and passes all requests
+ for non-static information to a regular userspace-webserver such as Apache
+ or Zeus. The userspace-daemon doesn't have to be altered in any way.
Static web-pages are not a very complex thing to serve, but these are very
important nevertheless, since virtually all images are static, and a large
portion of the html-pages are static also. A "regular" webserver has little
- added value for static pages, it is simply a "copy file to
network"-operation.
+ added value for static pages, it is simply a "copy file to network"
+ operation.
This can be done very efficiently from within the Linux-kernel, for example
the nfs (network file system) daemon performs a similar task and also runs
in the kernel.
@@ -44,6 +45,7 @@
echo 1 > /proc/sys/net/khttpd/stop
echo 1 > /proc/sys/net/khttpd/unload
+ sleep 2
rmmod khttpd
@@ -71,7 +73,7 @@
Before you can start using kHTTPd, you have to configure it. This
is done through the /proc filesystem, and can thus be done from inside
- a script. Most parameters can only be set when kHTTPd is not active.
+ a script. Most parameters can only be set when kHTTPd is stopped.
The following things need configuration:
@@ -117,26 +119,31 @@
Port 8080
+ Starting kHTTPd
+ ===============
+ Once you have set up the configuration, start kHTTPD by running
+ echo 1 > /proc/sys/net/khttpd/start
+ It may take a jiffie or two to start.
-
Stopping kHTTPd
===============
- In order to change the configuration, you should stop kHTTPd by typing
+ To stop kHTTPd, do
echo 1 > /proc/sys/net/khttpd/stop
- on a command-prompt.
+ It should stop in a jiffy or two.
- If you want to unload the module, you should type
+ Unloading kHTTPd
+ ===============
+ To unload the module, do
+ echo 1 > /proc/sys/net/khttpd/stop
echo 1 > /proc/sys/net/khttpd/unload
- after stopping kHTTPd first.
+ #killall -HUP khttpd
+ sleep 2
+ rmmod khttpd
- If this doesn't work fast enough for you (the commands above can wait for
+ If this doesn't work fast enough for you (unloading can wait for
a remote connection to close down), you can send the daemons a "HUP"
signal after you told them to stop. This will cause the daemon-threads to
stop immediately.
-
- Note that the daemons will restart immediately if they are not told to
- stop.
-
4. Permissions
@@ -212,7 +219,21 @@
maxconnect 1000 Maximum number of concurrent
connections
-6. More information
+6. Known Issues
+ kHTTPd is *not* currently compatible with tmpfs. Trying to serve
+ files stored on a tmpfs partition is known to cause kernel oopses
+ as of 2.4.18. This is due to the same problem that prevents sendfile()
+ from being usable with tmpfs. A tmpfs patch is floating around that seems
+ to fix this, but has not been released as of 27 May 2002.
+ kHTTPD does work fine with ramfs, though.
+
+ There is debate about whether to remove kHTTPd from the main
+ kernel sources. This will probably happen in the 2.5 kernel series,
+ after which khttpd will still be available as a patch.
+
+ The kHTTPd source code could use a good spring cleaning.
+
+7. More information
-------------------
More information about the architecture of kHTTPd, the mailinglist and
configuration-examples can be found at the kHTTPd homepage:
@@ -221,4 +242,6 @@
Bugreports, patches, etc can be send to the mailinglist
(khttpd-users@xxxxxxx) or to khttpd@xxxxxxxxxxxxxxx
+ Mailing list archives are at
+ http://lists.alt.org/mailman/listinfo/khttpd-users
diff -x '*times*' -x '.*' -x '*.o' -Naur linux-2.4.17-orig/net/khttpd/main.c
linux/net/khttpd/main.c
--- linux-2.4.17-orig/net/khttpd/main.c Sun Mar 25 18:14:25 2001
+++ linux/net/khttpd/main.c Mon May 27 23:17:08 2002
@@ -95,11 +95,17 @@
{
int CPUNR;
sigset_t tmpsig;
+ int old_stop_count;
DECLARE_WAITQUEUE(main_wait,current);
MOD_INC_USE_COUNT;
+ /* Remember value of stop count. If it changes, user must have
+ * asked us to stop. Sensing this is much less racy than
+ * directly sensing sysctl_khttpd_stop. - dank
+ */
+ old_stop_count = atomic_read(&khttpd_stopCount);
CPUNR=0;
if (cpu_pointer!=NULL)
@@ -125,11 +131,9 @@
atomic_inc(&DaemonCount);
atomic_set(&Running[CPUNR],1);
- while (sysctl_khttpd_stop==0)
+ while (old_stop_count == atomic_read(&khttpd_stopCount))
{
int changes = 0;
-
-
changes +=AcceptConnections(CPUNR,MainSocket);
if (ConnectionsPending(CPUNR))
@@ -194,11 +198,9 @@
DECLARE_WAIT_QUEUE_HEAD(WQ);
-
sprintf(current->comm,"khttpd manager");
daemonize();
-
/* Block all signals except SIGKILL and SIGSTOP */
spin_lock_irq(¤t->sigmask_lock);
tmpsig = current->blocked;
@@ -206,42 +208,35 @@
recalc_sigpending(current);
spin_unlock_irq(¤t->sigmask_lock);
-
/* main loop */
while (sysctl_khttpd_unload==0)
{
int I;
-
+ int old_stop_count;
/* First : wait for activation */
-
- sysctl_khttpd_start = 0;
-
while ( (sysctl_khttpd_start==0) && (!signal_pending(current))
&& (sysctl_khttpd_unload==0) )
{
current->state = TASK_INTERRUPTIBLE;
interruptible_sleep_on_timeout(&WQ,HZ);
}
-
if ( (signal_pending(current)) || (sysctl_khttpd_unload!=0) )
break;
+ sysctl_khttpd_stop = 0;
/* Then start listening and spawn the daemons */
-
if (StartListening(sysctl_khttpd_serverport)==0)
{
+ sysctl_khttpd_start = 0;
continue;
}
-
+
ActualThreads = sysctl_khttpd_threads;
if (ActualThreads<1)
ActualThreads = 1;
-
if (ActualThreads>CONFIG_KHTTPD_NUMCPU)
ActualThreads = CONFIG_KHTTPD_NUMCPU;
-
/* Write back the actual value */
-
sysctl_khttpd_threads = ActualThreads;
InitUserspace(ActualThreads);
@@ -249,87 +244,63 @@
if (InitDataSending(ActualThreads)!=0)
{
StopListening();
+ sysctl_khttpd_start = 0;
continue;
}
if (InitWaitHeaders(ActualThreads)!=0)
{
- I=0;
- while (I<ActualThreads)
- {
+ for (I=0; I<ActualThreads; I++) {
StopDataSending(I);
- I++;
}
StopListening();
+ sysctl_khttpd_start = 0;
continue;
}
/* Clean all queues */
memset(threadinfo, 0, sizeof(struct khttpd_threadinfo));
-
-
- I=0;
- while (I<ActualThreads)
- {
+ for (I=0; I<ActualThreads; I++) {
atomic_set(&Running[I],1);
(void)kernel_thread(MainDaemon,&(CountBuf[I]), CLONE_FS
| CLONE_FILES | CLONE_SIGHAND);
- I++;
}
/* Then wait for deactivation */
- sysctl_khttpd_stop = 0;
-
- while ( (sysctl_khttpd_stop==0) && (!signal_pending(current))
&& (sysctl_khttpd_unload==0) )
+ /* Remember value of stop count. If it changes, user must
+ * have asked us to stop. Sensing this is much less racy
+ * than directly sensing sysctl_khttpd_stop. - dank
+ */
+ old_stop_count = atomic_read(&khttpd_stopCount);
+ while ( ( old_stop_count == atomic_read(&khttpd_stopCount))
+ && (!signal_pending(current))
+ && (sysctl_khttpd_unload==0) )
{
- if (atomic_read(&DaemonCount)<ActualThreads)
- {
- I=0;
- while (I<ActualThreads)
- {
- if (atomic_read(&Running[I])==0)
- {
- atomic_set(&Running[I],1);
-
(void)kernel_thread(MainDaemon,&(CountBuf[I]), CLONE_FS | CLONE_FILES |
CLONE_SIGHAND);
- (void)printk(KERN_CRIT "kHTTPd:
Restarting daemon %i \n",I);
- }
- I++;
- }
- }
+ /* Used to restart dead threads here, but it was buggy*/
interruptible_sleep_on_timeout(&WQ,HZ);
-
- /* reap the daemons */
- waitpid_result = waitpid(-1,NULL,__WCLONE|WNOHANG);
-
}
-
- /* The user wants us to stop. So stop listening on the socket.
*/
- if (sysctl_khttpd_stop!=0)
- {
- /* Wait for the daemons to stop, one second per
iteration */
- while (atomic_read(&DaemonCount)>0)
- interruptible_sleep_on_timeout(&WQ,HZ);
- StopListening();
- }
-
-
-
+ /* Wait for the daemons to stop, one second per iteration */
+ while (atomic_read(&DaemonCount)>0)
+ interruptible_sleep_on_timeout(&WQ,HZ);
+ StopListening();
+ sysctl_khttpd_start = 0;
+ /* reap the zombie-daemons */
+ do
+ waitpid_result = waitpid(-1,NULL,__WCLONE|WNOHANG);
+ while (waitpid_result>0);
}
-
+ sysctl_khttpd_start = 0;
sysctl_khttpd_stop = 1;
+ atomic_inc(&khttpd_stopCount);
/* Wait for the daemons to stop, one second per iteration */
while (atomic_read(&DaemonCount)>0)
interruptible_sleep_on_timeout(&WQ,HZ);
-
-
- waitpid_result = 1;
+ StopListening();
/* reap the zombie-daemons */
- while (waitpid_result>0)
+ do
waitpid_result = waitpid(-1,NULL,__WCLONE|WNOHANG);
-
- StopListening();
-
+ while (waitpid_result>0);
(void)printk(KERN_NOTICE "kHTTPd: Management daemon stopped. \n
You can unload the module now.\n");
@@ -344,16 +315,13 @@
MOD_INC_USE_COUNT;
- I=0;
- while (I<CONFIG_KHTTPD_NUMCPU)
- {
+ for (I=0; I<CONFIG_KHTTPD_NUMCPU; I++) {
CountBuf[I]=I;
-
- I++;
}
atomic_set(&ConnectCount,0);
atomic_set(&DaemonCount,0);
+ atomic_set(&khttpd_stopCount,0);
/* Maybe the mime-types will be set-able through sysctl in the future
*/
diff -x '*times*' -x '.*' -x '*.o' -Naur linux-2.4.17-orig/net/khttpd/sysctl.c
linux/net/khttpd/sysctl.c
--- linux-2.4.17-orig/net/khttpd/sysctl.c Fri Feb 9 11:34:13 2001
+++ linux/net/khttpd/sysctl.c Mon May 27 18:55:19 2002
@@ -64,6 +64,7 @@
int sysctl_khttpd_threads = 2;
int sysctl_khttpd_maxconnect = 1000;
+atomic_t khttpd_stopCount;
static struct ctl_table_header *khttpd_table_header;
@@ -72,6 +73,8 @@
void *newval, size_t newlen, void **context);
static int proc_dosecurestring(ctl_table *table, int write, struct file *filp,
void *buffer, size_t *lenp);
+static int khttpd_stop_wrap_proc_dointvec(ctl_table *table, int write, struct
file *filp,
+ void *buffer, size_t *lenp);
static ctl_table khttpd_table[] = {
@@ -93,7 +96,7 @@
sizeof(int),
0644,
NULL,
- proc_dointvec,
+ khttpd_stop_wrap_proc_dointvec,
&sysctl_intvec,
NULL,
NULL,
@@ -307,6 +310,24 @@
return 0;
}
+/* A wrapper around proc_dointvec that computes
+ * khttpd_stopCount = # of times sysctl_khttpd_stop has gone true
+ * Sensing sysctl_khttpd_stop in other threads is racy;
+ * sensing khttpd_stopCount in other threads is not.
+ */
+static int khttpd_stop_wrap_proc_dointvec(ctl_table *table, int write, struct
file *filp,
+ void *buffer, size_t *lenp)
+{
+ int rv;
+ int oldstop = sysctl_khttpd_stop;
+ rv = proc_dointvec(table, write, filp, buffer, lenp);
+ if (sysctl_khttpd_stop && !oldstop)
+ atomic_inc(&khttpd_stopCount);
+
+ return rv;
+}
+
+
static int sysctl_SecureString (/*@unused@*/ctl_table *table,
/*@unused@*/int *name,
/*@unused@*/int nlen,
diff -x '*times*' -x '.*' -x '*.o' -Naur linux-2.4.17-orig/net/khttpd/sysctl.h
linux/net/khttpd/sysctl.h
--- linux-2.4.17-orig/net/khttpd/sysctl.h Wed Aug 18 09:45:10 1999
+++ linux/net/khttpd/sysctl.h Mon May 27 17:56:28 2002
@@ -14,4 +14,7 @@
extern int sysctl_khttpd_threads;
extern int sysctl_khttpd_maxconnect;
+/* incremented each time sysctl_khttpd_stop goes nonzero */
+extern atomic_t khttpd_stopCount;
+
#endif
diff -x '*times*' -x '.*' -x '*.o' -Naur
linux-2.4.17-orig/net/khttpd/waitheaders.c linux/net/khttpd/waitheaders.c
--- linux-2.4.17-orig/net/khttpd/waitheaders.c Mon Sep 10 07:57:00 2001
+++ linux/net/khttpd/waitheaders.c Mon May 27 17:56:28 2002
@@ -134,7 +134,7 @@
CurrentRequest = CurrentRequest->Next;
}
- LeaveFunction("WaitHeaders");
+ LeaveFunction("WaitForHeaders");
return count;
}
@@ -178,6 +178,12 @@
EnterFunction("DecodeHeader");
+ if (Buffer[CPUNR] == NULL) {
+ /* see comments in main.c regarding buffer managemnet - dank */
+ printk(KERN_CRIT "khttpd: lost my buffer");
+ BUG();
+ }
+
/* First, read the data */
msg.msg_name = 0;
--- linux-2.4.17-orig/Documentation/networking/khttpd.txt Wed Dec 31
16:00:00 1969
+++ linux/Documentation/networking/khttpd.txt Mon May 27 23:19:03 2002
@@ -0,0 +1 @@
+See net/khttpd/README for documentation on khttpd, the kernel http server.
|