[PATCH] uml: Fix SIGWINCH relaying

This makes SIGWINCH work again, and fixes a couple of SIGWINCH-associated crashes. First, the sigio thread disables SIGWINCH because all hell breaks loose if it ever gets one and tries to call the signal handling code. Second, there was a problem with deferencing tty structs after they were freed. The SIGWINCH support for a tty wasn't being turned off or freed after the tty went away. Signed-off-by: Jeff Dike <jdike@addtoit.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>

[PATCH] uml: Fix SIGWINCH relaying
This makes SIGWINCH work again, and fixes a couple of SIGWINCH-associated crashes. First, the sigio thread disables SIGWINCH because all hell breaks loose if it ever gets one and tries to call the signal handling code. Second, there was a problem with deferencing tty structs after they were freed. The SIGWINCH support for a tty wasn't being turned off or freed after the tty went away. Signed-off-by: Jeff Dike <jdike@addtoit.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Jeff Dike · Linus Torvalds
1 parent c578455a3e
Showing 8 changed files with 55 additions and 7 deletions Side-by-side Diff
arch/um/drivers/line.c
arch/um/include/os.h
arch/um/kernel/irq.c
arch/um/kernel/process.c
arch/um/kernel/sigio_user.c
arch/um/kernel/skas/process.c
arch/um/kernel/tt/tracer.c
arch/um/os-Linux/process.c
@@ -462,12 +462,15 @@
 	return err;
 }
  
+static void unregister_winch(struct tty_struct *tty);
+
 void line_close(struct tty_struct *tty, struct file * filp)
 {
 	struct line *line = tty->driver_data;
  
-	/* XXX: I assume this should be called in process context, not with interrupt
-	 * disabled!*/
+	/* XXX: I assume this should be called in process context, not with
+         *  interrupts disabled!
+         */
 	spin_lock_irq(&line->lock);
  
 	/* We ignore the error anyway! */
@@ -478,6 +481,12 @@
 		line_disable(tty, -1);
 		tty->driver_data = NULL;
 	}
+
+        if((line->count == 0) && line->sigio){
+                unregister_winch(tty);
+                line->sigio = 0;
+        }
+
 	spin_unlock_irq(&line->lock);
 }
  
@@ -725,6 +734,34 @@
 			  SA_INTERRUPT | SA_SHIRQ | SA_SAMPLE_RANDOM, 
 			  "winch", winch) < 0)
 		printk("register_winch_irq - failed to register IRQ\n");
+ out:
+	up(&winch_handler_sem);
+}
+
+static void unregister_winch(struct tty_struct *tty)
+{
+	struct list_head *ele;
+	struct winch *winch, *found = NULL;
+
+	down(&winch_handler_sem);
+	list_for_each(ele, &winch_handlers){
+		winch = list_entry(ele, struct winch, list);
+                if(winch->tty == tty){
+                        found = winch;
+                        break;
+                }
+        }
+
+        if(found == NULL)
+                goto out;
+
+        if(winch->pid != -1)
+                os_kill_process(winch->pid, 1);
+
+        free_irq_by_irq_and_dev(WINCH_IRQ, winch);
+        free_irq(WINCH_IRQ, winch);
+        list_del(&winch->list);
+        kfree(winch);
  out:
 	up(&winch_handler_sem);
 }
@@ -160,6 +160,7 @@
 extern void os_kill_ptraced_process(int pid, int reap_child);
 extern void os_usr1_process(int pid);
 extern int os_getpid(void);
+extern int os_getpgrp(void);
  
 extern int os_map_memory(void *virt, int fd, unsigned long long off,
 			 unsigned long len, int r, int w, int x);
@@ -163,7 +163,6 @@
 		irq_desc[i].handler = &SIGIO_irq_type;
 		enable_irq(i);
 	}
-	init_irq_signals(0);
 }
  
 /*
@@ -65,8 +65,6 @@
 		    SIGUSR1, SIGIO, SIGWINCH, SIGALRM, SIGVTALRM, -1);
 	set_handler(SIGBUS, (__sighandler_t) sig_handler, flags, 
 		    SIGUSR1, SIGIO, SIGWINCH, SIGALRM, SIGVTALRM, -1);
-	set_handler(SIGWINCH, (__sighandler_t) sig_handler, flags, 
-		    SIGUSR1, SIGIO, SIGWINCH, SIGALRM, SIGVTALRM, -1);
 	set_handler(SIGUSR2, (__sighandler_t) sig_handler, 
 		    flags, SIGUSR1, SIGIO, SIGWINCH, SIGALRM, SIGVTALRM, -1);
 	signal(SIGHUP, SIG_IGN);
@@ -182,6 +182,7 @@
 	int i, n, respond_fd;
 	char c;
  
+        signal(SIGWINCH, SIG_IGN);
 	fds = &current_poll;
 	while(1){
 		n = poll(fds->poll, fds->used, -1);
@@ -28,10 +28,11 @@
 #include "chan_user.h"
 #include "signal_user.h"
 #include "registers.h"
+#include "process.h"
  
 int is_skas_winch(int pid, int fd, void *data)
 {
-	if(pid != os_getpid())
+        if(pid != os_getpgrp())
 		return(0);
  
 	register_winch_irq(-1, fd, -1, data);
@@ -258,6 +259,10 @@
 {
 	sigjmp_buf **switch_buf = switch_buf_ptr;
 	int n;
+
+	set_handler(SIGWINCH, (__sighandler_t) sig_handler,
+		    SA_ONSTACK | SA_RESTART, SIGUSR1, SIGIO, SIGALRM,
+		    SIGVTALRM, -1);
  
 	*fork_buf_ptr = &initial_jmpbuf;
 	n = sigsetjmp(initial_jmpbuf, 1);
@@ -26,6 +26,7 @@
 #include "kern_util.h"
 #include "chan_user.h"
 #include "ptrace_user.h"
+#include "irq_user.h"
 #include "mode.h"
 #include "tt.h"
  
@@ -33,7 +34,7 @@
  
 int is_tracer_winch(int pid, int fd, void *data)
 {
-	if(pid != tracing_pid)
+	if(pid != os_getpgrp())
 		return(0);
  
 	register_winch_irq(tracer_winch[0], fd, -1, data);
@@ -119,6 +120,7 @@
 	signal(SIGSEGV, (__sighandler_t) sig_handler);
 	set_cmdline("(idle thread)");
 	set_init_pid(os_getpid());
+	init_irq_signals(0);
 	proc = arg;
 	return((*proc)(NULL));
 }
@@ -123,6 +123,11 @@
 	return(getpid());
 }
  
+int os_getpgrp(void)
+{
+	return getpgrp();
+}
+
 int os_map_memory(void *virt, int fd, unsigned long long off, unsigned long len,
 		  int r, int w, int x)
 {
...	...	@@ -462,12 +462,15 @@
462	462	return err;
463	463	}
464	464
	465	+static void unregister_winch(struct tty_struct *tty);
	466	+
465	467	void line_close(struct tty_struct tty, struct file filp)
466	468	{
467	469	struct line *line = tty->driver_data;
468	470
469		- /* XXX: I assume this should be called in process context, not with interrupt
470		- * disabled!*/
	471	+ /* XXX: I assume this should be called in process context, not with
	472	+ * interrupts disabled!
	473	+ */
471	474	spin_lock_irq(&line->lock);
472	475
473	476	/* We ignore the error anyway! */
...	...	@@ -478,6 +481,12 @@
478	481	line_disable(tty, -1);
479	482	tty->driver_data = NULL;
480	483	}
	484	+
	485	+ if((line->count == 0) && line->sigio){
	486	+ unregister_winch(tty);
	487	+ line->sigio = 0;
	488	+ }
	489	+
481	490	spin_unlock_irq(&line->lock);
482	491	}
483	492
...	...	@@ -725,6 +734,34 @@
725	734	SA_INTERRUPT \| SA_SHIRQ \| SA_SAMPLE_RANDOM,
726	735	"winch", winch) < 0)
727	736	printk("register_winch_irq - failed to register IRQ\n");
	737	+ out:
	738	+ up(&winch_handler_sem);
	739	+}
	740	+
	741	+static void unregister_winch(struct tty_struct *tty)
	742	+{
	743	+ struct list_head *ele;
	744	+ struct winch winch, found = NULL;
	745	+
	746	+ down(&winch_handler_sem);
	747	+ list_for_each(ele, &winch_handlers){
	748	+ winch = list_entry(ele, struct winch, list);
	749	+ if(winch->tty == tty){
	750	+ found = winch;
	751	+ break;
	752	+ }
	753	+ }
	754	+
	755	+ if(found == NULL)
	756	+ goto out;
	757	+
	758	+ if(winch->pid != -1)
	759	+ os_kill_process(winch->pid, 1);
	760	+
	761	+ free_irq_by_irq_and_dev(WINCH_IRQ, winch);
	762	+ free_irq(WINCH_IRQ, winch);
	763	+ list_del(&winch->list);
	764	+ kfree(winch);
728	765	out:
729	766	up(&winch_handler_sem);
730	767	}
...	...	@@ -160,6 +160,7 @@
160	160	extern void os_kill_ptraced_process(int pid, int reap_child);
161	161	extern void os_usr1_process(int pid);
162	162	extern int os_getpid(void);
	163	+extern int os_getpgrp(void);
163	164
164	165	extern int os_map_memory(void *virt, int fd, unsigned long long off,
165	166	unsigned long len, int r, int w, int x);
...	...	@@ -163,7 +163,6 @@
163	163	irq_desc[i].handler = &SIGIO_irq_type;
164	164	enable_irq(i);
165	165	}
166		- init_irq_signals(0);
167	166	}
168	167
169	168	/*
...	...	@@ -65,8 +65,6 @@
65	65	SIGUSR1, SIGIO, SIGWINCH, SIGALRM, SIGVTALRM, -1);
66	66	set_handler(SIGBUS, (__sighandler_t) sig_handler, flags,
67	67	SIGUSR1, SIGIO, SIGWINCH, SIGALRM, SIGVTALRM, -1);
68		- set_handler(SIGWINCH, (__sighandler_t) sig_handler, flags,
69		- SIGUSR1, SIGIO, SIGWINCH, SIGALRM, SIGVTALRM, -1);
70	68	set_handler(SIGUSR2, (__sighandler_t) sig_handler,
71	69	flags, SIGUSR1, SIGIO, SIGWINCH, SIGALRM, SIGVTALRM, -1);
72	70	signal(SIGHUP, SIG_IGN);
...	...	@@ -182,6 +182,7 @@
182	182	int i, n, respond_fd;
183	183	char c;
184	184
	185	+ signal(SIGWINCH, SIG_IGN);
185	186	fds = &current_poll;
186	187	while(1){
187	188	n = poll(fds->poll, fds->used, -1);
...	...	@@ -28,10 +28,11 @@
28	28	#include "chan_user.h"
29	29	#include "signal_user.h"
30	30	#include "registers.h"
	31	+#include "process.h"
31	32
32	33	int is_skas_winch(int pid, int fd, void *data)
33	34	{
34		- if(pid != os_getpid())
	35	+ if(pid != os_getpgrp())
35	36	return(0);
36	37
37	38	register_winch_irq(-1, fd, -1, data);
...	...	@@ -258,6 +259,10 @@
258	259	{
259	260	sigjmp_buf **switch_buf = switch_buf_ptr;
260	261	int n;
	262	+
	263	+ set_handler(SIGWINCH, (__sighandler_t) sig_handler,
	264	+ SA_ONSTACK \| SA_RESTART, SIGUSR1, SIGIO, SIGALRM,
	265	+ SIGVTALRM, -1);
261	266
262	267	*fork_buf_ptr = &initial_jmpbuf;
263	268	n = sigsetjmp(initial_jmpbuf, 1);
...	...	@@ -26,6 +26,7 @@
26	26	#include "kern_util.h"
27	27	#include "chan_user.h"
28	28	#include "ptrace_user.h"
	29	+#include "irq_user.h"
29	30	#include "mode.h"
30	31	#include "tt.h"
31	32
...	...	@@ -33,7 +34,7 @@
33	34
34	35	int is_tracer_winch(int pid, int fd, void *data)
35	36	{
36		- if(pid != tracing_pid)
	37	+ if(pid != os_getpgrp())
37	38	return(0);
38	39
39	40	register_winch_irq(tracer_winch[0], fd, -1, data);
...	...	@@ -119,6 +120,7 @@
119	120	signal(SIGSEGV, (__sighandler_t) sig_handler);
120	121	set_cmdline("(idle thread)");
121	122	set_init_pid(os_getpid());
	123	+ init_irq_signals(0);
122	124	proc = arg;
123	125	return((*proc)(NULL));
124	126	}
...	...	@@ -123,6 +123,11 @@
123	123	return(getpid());
124	124	}
125	125
	126	+int os_getpgrp(void)
	127	+{
	128	+ return getpgrp();
	129	+}
	130	+
126	131	int os_map_memory(void *virt, int fd, unsigned long long off, unsigned long len,
127	132	int r, int w, int x)
128	133	{