Commit 3a51237d authored by Al Viro's avatar Al Viro Committed by Linus Torvalds
Browse files

[PATCH] uml: mconsole fixes

 * when we have stop/sysrq/go, we get pt_regs of whatever executes
   mc_work_proc().  Would be better to see what we had at the time of
   interrupt that got us stop.

 * stop/stop/stop.....  will give stack overflow.  Shouldn't allow stop
   from mconsole_stop().

 * stop/stop/go leaves us inside mconsole_stop() with
	os_set_fd_block(req->originating_fd, 0);
	reactivate_fd(req->originating_fd, MCONSOLE_IRQ);
   just done by nested mconsole_stop().  Ditto.

 * once we'd seen stop, there's a period when INTR commands are executed
   out of order (as they should; we might have the things stuck badly
   enough to never reach mconsole_stop(), but still not badly enough to
   block mconsole_interrupt(); in that situation we _want_ things like
   "cad" to be executed immediately).  Once we enter monsole_stop(), all
   INTR commands will be executed in order, mixed with PROC ones.  We'd
   better let user see that such change of behaviour has happened.
   (Suggested by lennert).

 * stack footprint of monsole_interrupt() is an atrocity; AFAICS we can
   safely make struct mc_request req; static in function there.
Signed-off-by: default avatarAl Viro <>
Acked-by: default avatarJeff Dike <>
Signed-off-by: default avatarLinus Torvalds <>
parent 6c504447
......@@ -79,7 +79,7 @@ static irqreturn_t mconsole_interrupt(int irq, void *dev_id)
/* long to avoid size mismatch warnings from gcc */
long fd;
struct mconsole_entry *new;
struct mc_request req;
static struct mc_request req; /* that's OK */
fd = (long) dev_id;
while (mconsole_get_request(fd, &req)){
......@@ -91,6 +91,7 @@ static irqreturn_t mconsole_interrupt(int irq, void *dev_id)
mconsole_reply(&req, "Out of memory", 1, 0);
else {
new->request = req;
new->request.regs = get_irq_regs()->regs;
list_add(&new->list, &mc_requests);
......@@ -314,9 +315,21 @@ void mconsole_stop(struct mc_request *req)
deactivate_fd(req->originating_fd, MCONSOLE_IRQ);
os_set_fd_block(req->originating_fd, 1);
mconsole_reply(req, "", 0, 0);
while(mconsole_get_request(req->originating_fd, req)){
if(req->cmd->handler == mconsole_go) break;
mconsole_reply(req, "stopped", 0, 0);
while (mconsole_get_request(req->originating_fd, req)) {
if (req->cmd->handler == mconsole_go)
if (req->cmd->handler == mconsole_stop) {
mconsole_reply(req, "Already stopped", 1, 0);
if (req->cmd->handler == mconsole_sysrq) {
struct pt_regs *old_regs;
old_regs = set_irq_regs((struct pt_regs *)&req->regs);
os_set_fd_block(req->originating_fd, 0);
......@@ -673,9 +686,7 @@ static void with_console(struct mc_request *req, void (*proc)(void *),
static void sysrq_proc(void *arg)
char *op = arg;
struct pt_regs *old_regs = set_irq_regs(&current->thread.regs);
handle_sysrq(*op, NULL);
void mconsole_sysrq(struct mc_request *req)
......@@ -14,6 +14,7 @@
#include <sys/un.h>
#include <unistd.h>
#include "user.h"
#include "sysdep/ptrace.h"
#include "mconsole.h"
#include "umid.h"
#include "user_util.h"
......@@ -61,6 +61,7 @@ struct mc_request
struct mconsole_request request;
struct mconsole_command *cmd;
union uml_pt_regs regs;
extern char mconsole_socket_name[];
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