@@ -38,7 +38,7 @@ static int info_show(struct seq_file *s, void *private)
seq_printf(s, "Type: %s, %s\n", cop_to_str(window->cop),
window->tx_win ? "Send" : "Receive");
- seq_printf(s, "Pid : %d\n", window->pid);
+ seq_printf(s, "Pid : %d\n", vas_window_pid(window));
unlock:
mutex_unlock(&vas_mutex);
@@ -12,6 +12,8 @@
#include <linux/log2.h>
#include <linux/rcupdate.h>
#include <linux/cred.h>
+#include <linux/sched/mm.h>
+#include <linux/mmu_context.h>
#include <asm/switch_to.h>
#include <asm/ppc-opcode.h>
#include "vas.h"
@@ -887,8 +889,6 @@ struct vas_window *vas_rx_win_open(int vasid, enum vas_cop_type cop,
rxwin->user_win = rxattr->user_win;
rxwin->cop = cop;
rxwin->wcreds_max = rxattr->wcreds_max ?: VAS_WCREDS_DEFAULT;
- if (rxattr->user_win)
- rxwin->pid = task_pid_vnr(current);
init_winctx_for_rxwin(rxwin, rxattr, &winctx);
init_winctx_regs(rxwin, &winctx);
@@ -1037,7 +1037,6 @@ struct vas_window *vas_tx_win_open(int vasid, enum vas_cop_type cop,
txwin->tx_win = 1;
txwin->rxwin = rxwin;
txwin->nx_win = txwin->rxwin->nx_win;
- txwin->pid = attr->pid;
txwin->user_win = attr->user_win;
txwin->wcreds_max = attr->wcreds_max ?: VAS_WCREDS_DEFAULT;
@@ -1079,6 +1078,34 @@ struct vas_window *vas_tx_win_open(int vasid, enum vas_cop_type cop,
goto free_window;
}
+ if (txwin->user_win) {
+ /*
+ * Window opened by child thread may not be closed when
+ * it exits. So take reference to its pid and release it
+ * when the window is free by parent thread.
+ * Acquire a reference to the task's pid to make sure
+ * pid will not be re-used.
+ */
+ txwin->pid = get_task_pid(current, PIDTYPE_PID);
+ /*
+ * Acquire a reference to the task's mm.
+ */
+ txwin->mm = get_task_mm(current);
+
+ if (txwin->mm) {
+ mmput(txwin->mm);
+ mmgrab(txwin->mm);
+ mm_context_add_copro(txwin->mm);
+ } else {
+ put_pid(txwin->pid);
+ pr_err("VAS: pid(%d): mm_struct is not found\n",
+ current->pid);
+ rc = -EPERM;
+ goto free_window;
+ }
+ txwin->tgid = task_tgid_vnr(current);
+ }
+
set_vinst_win(vinst, txwin);
return txwin;
@@ -1277,8 +1304,17 @@ int vas_win_close(struct vas_window *window)
poll_window_castout(window);
/* if send window, drop reference to matching receive window */
- if (window->tx_win)
+ if (window->tx_win) {
+ if (window->user_win) {
+ /* Drop references to pid and mm */
+ put_pid(window->pid);
+ if (window->mm) {
+ mmdrop(window->mm);
+ mm_context_remove_copro(window->mm);
+ }
+ }
put_rx_win(window->rxwin);
+ }
vas_window_free(window);
@@ -343,7 +343,9 @@ struct vas_window {
bool user_win; /* True if user space window */
void *hvwc_map; /* HV window context */
void *uwc_map; /* OS/User window context */
- pid_t pid; /* Linux process id of owner */
+ struct pid *pid; /* Linux process id of owner */
+ pid_t tgid; /* Thread group ID of owner */
+ struct mm_struct *mm; /* Linux process mm_struct */
int wcreds_max; /* Window credits */
char *dbgname;
@@ -424,6 +426,16 @@ struct vas_winctx {
extern struct vas_window *vas_pswid_to_window(struct vas_instance *vinst,
uint32_t pswid);
+static inline int vas_window_pid(struct vas_window *window)
+{
+ return pid_vnr(window->pid);
+}
+
+static inline int vas_window_tgid(struct vas_window *window)
+{
+ return window->tgid;
+}
+
static inline void vas_log_write(struct vas_window *win, char *name,
void *regptr, u64 val)
{
Process close windows after its requests are completed. In multi-thread applications, child can open a window but release FD will not be called upon its exit. Parent thread will be closing it later upon its exit. The parent can also send NX requests with this window and NX can generate page faults. After kernel handles the page fault, send signal to process by using PID if CSB address is invalid. Parent thread will not receive signal since its PID is different from the one saved in vas_window. So use tgid in case if the task for the pid saved in window is not running and send signal to its parent. To prevent reusing the pid until the window closed, take reference to pid and task mm. Signed-off-by: Haren Myneni <haren@us.ibm.com> --- arch/powerpc/platforms/powernv/vas-debug.c | 2 +- arch/powerpc/platforms/powernv/vas-window.c | 44 ++++++++++++++++++++++++++--- arch/powerpc/platforms/powernv/vas.h | 14 ++++++++- 3 files changed, 54 insertions(+), 6 deletions(-)