linux-kernel - [PATCH] h8300: fix syscall restarting

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Date:   Mon, 26 Sep 2016 20:33:54 +0100
From:   Mark Rutland <mark.rutland@....com>
To:     ysato@...rs.sourceforge.jp
Cc:     luto@...capital.net, linux-kernel@...r.kernel.org,
        uclinux-h8-devel@...ts.sourceforge.jp
Subject: [PATCH] h8300: fix syscall restarting

Back in commit f56141e3e2d9aabf ("all arches, signal: move restart_block
to struct task_struct"), all architectures and core code were changed to
use task_struct::restart_block. However, when h8300 support was
subsequently restored in v4.2, it was not updated to account for this,
and maintains thread_info::restart_block, which is not kept in sync.

This patch drops the redundant restart_block from thread_info, and moves
h8300 to the common one in task_struct, ensuring that syscall restarting
always works as expected.

Signed-off-by: Mark Rutland <mark.rutland@....com>
Cc: Andy Lutomirski <luto@...capital.net>
Cc: Yoshinori Sato <ysato@...rs.sourceforge.jp>
Cc: linux-kernel@...r.kernel.org
Cc: stable@...r.kernel.org # v4.2+
Cc: uclinux-h8-devel@...ts.sourceforge.jp
---
 arch/h8300/include/asm/thread_info.h | 4 ----
 arch/h8300/kernel/signal.c           | 2 +-
 2 files changed, 1 insertion(+), 5 deletions(-)

Hi,

While looking into some arm64 rework I spooted this issue with h8300. I
previously sent this in reply [1] to another patch, so I guess no-one spotted
it.

Thanks,
Mark.

[1] http://lkml.kernel.org/r/20160919104254.GA12473@leverpostej

diff --git a/arch/h8300/include/asm/thread_info.h b/arch/h8300/include/asm/thread_info.h
index b408fe6..3cef068 100644
--- a/arch/h8300/include/asm/thread_info.h
+++ b/arch/h8300/include/asm/thread_info.h
@@ -31,7 +31,6 @@ struct thread_info {
 	int		   cpu;			/* cpu we're on */
 	int		   preempt_count;	/* 0 => preemptable, <0 => BUG */
 	mm_segment_t		addr_limit;
-	struct restart_block restart_block;
 };
 
 /*
@@ -44,9 +43,6 @@ struct thread_info {
 	.cpu =		0,			\
 	.preempt_count = INIT_PREEMPT_COUNT,	\
 	.addr_limit	= KERNEL_DS,		\
-	.restart_block	= {			\
-		.fn = do_no_restart_syscall,	\
-	},					\
 }
 
 #define init_thread_info	(init_thread_union.thread_info)
diff --git a/arch/h8300/kernel/signal.c b/arch/h8300/kernel/signal.c
index ad1f81f..7138303 100644
--- a/arch/h8300/kernel/signal.c
+++ b/arch/h8300/kernel/signal.c
@@ -79,7 +79,7 @@ restore_sigcontext(struct sigcontext *usc, int *pd0)
 	unsigned int er0;
 
 	/* Always make any pending restarted system calls return -EINTR */
-	current_thread_info()->restart_block.fn = do_no_restart_syscall;
+	current->restart_block.fn = do_no_restart_syscall;
 
 	/* restore passed registers */
 #define COPY(r)  do { err |= get_user(regs->r, &usc->sc_##r); } while (0)
-- 
2.7.4