linux-kernel - [PATCH] signal: Don't init struct kernel

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Message-Id: <20201220074555.12655-1-lsahn@ooseel.net>
Date:   Sun, 20 Dec 2020 16:45:54 +0900
From:   Leesoo Ahn <dev@...eel.net>
To:     linux-kernel@...r.kernel.org
Cc:     Leesoo Ahn <lsahn@...eel.net>,
        Christian Brauner <christian.brauner@...ntu.com>,
        "Eric W. Biederman" <ebiederm@...ssion.com>,
        Oleg Nesterov <oleg@...hat.com>, Jens Axboe <axboe@...nel.dk>,
        Peter Collingbourne <pcc@...gle.com>,
        Zhiqiang Liu <liuzhiqiang26@...wei.com>
Subject: [PATCH] signal: Don't init struct kernel_siginfo fields to zero again

clear_siginfo() is responsible for clearing struct kernel_siginfo object.
It's obvious that manually initializing those fields is needless as
a commit[1] explains why the function introduced and its guarantee that
all bits in the struct are cleared after it.

[1]: commit 8c5dbf2ae00b ("signal: Introduce clear_siginfo")

Signed-off-by: Leesoo Ahn <lsahn@...eel.net>
---
 kernel/signal.c | 21 ---------------------
 1 file changed, 21 deletions(-)

diff --git a/kernel/signal.c b/kernel/signal.c
index 5736c55aaa1a..8f49fa3ade33 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -603,10 +603,7 @@ static void collect_signal(int sig, struct sigpending *list, kernel_siginfo_t *i
 		 */
 		clear_siginfo(info);
 		info->si_signo = sig;
-		info->si_errno = 0;
 		info->si_code = SI_USER;
-		info->si_pid = 0;
-		info->si_uid = 0;
 	}
 }
 
@@ -1120,7 +1117,6 @@ static int __send_signal(int sig, struct kernel_siginfo *info, struct task_struc
 		case (unsigned long) SEND_SIG_NOINFO:
 			clear_siginfo(&q->info);
 			q->info.si_signo = sig;
-			q->info.si_errno = 0;
 			q->info.si_code = SI_USER;
 			q->info.si_pid = task_tgid_nr_ns(current,
 							task_active_pid_ns(t));
@@ -1133,10 +1129,7 @@ static int __send_signal(int sig, struct kernel_siginfo *info, struct task_struc
 		case (unsigned long) SEND_SIG_PRIV:
 			clear_siginfo(&q->info);
 			q->info.si_signo = sig;
-			q->info.si_errno = 0;
 			q->info.si_code = SI_KERNEL;
-			q->info.si_pid = 0;
-			q->info.si_uid = 0;
 			break;
 		default:
 			copy_siginfo(&q->info, info);
@@ -1623,10 +1616,7 @@ void force_sig(int sig)
 
 	clear_siginfo(&info);
 	info.si_signo = sig;
-	info.si_errno = 0;
 	info.si_code = SI_KERNEL;
-	info.si_pid = 0;
-	info.si_uid = 0;
 	force_sig_info(&info);
 }
 EXPORT_SYMBOL(force_sig);
@@ -1659,7 +1649,6 @@ int force_sig_fault_to_task(int sig, int code, void __user *addr
 
 	clear_siginfo(&info);
 	info.si_signo = sig;
-	info.si_errno = 0;
 	info.si_code  = code;
 	info.si_addr  = addr;
 #ifdef __ARCH_SI_TRAPNO
@@ -1691,7 +1680,6 @@ int send_sig_fault(int sig, int code, void __user *addr
 
 	clear_siginfo(&info);
 	info.si_signo = sig;
-	info.si_errno = 0;
 	info.si_code  = code;
 	info.si_addr  = addr;
 #ifdef __ARCH_SI_TRAPNO
@@ -1712,7 +1700,6 @@ int force_sig_mceerr(int code, void __user *addr, short lsb)
 	WARN_ON((code != BUS_MCEERR_AO) && (code != BUS_MCEERR_AR));
 	clear_siginfo(&info);
 	info.si_signo = SIGBUS;
-	info.si_errno = 0;
 	info.si_code = code;
 	info.si_addr = addr;
 	info.si_addr_lsb = lsb;
@@ -1726,7 +1713,6 @@ int send_sig_mceerr(int code, void __user *addr, short lsb, struct task_struct *
 	WARN_ON((code != BUS_MCEERR_AO) && (code != BUS_MCEERR_AR));
 	clear_siginfo(&info);
 	info.si_signo = SIGBUS;
-	info.si_errno = 0;
 	info.si_code = code;
 	info.si_addr = addr;
 	info.si_addr_lsb = lsb;
@@ -1740,7 +1726,6 @@ int force_sig_bnderr(void __user *addr, void __user *lower, void __user *upper)
 
 	clear_siginfo(&info);
 	info.si_signo = SIGSEGV;
-	info.si_errno = 0;
 	info.si_code  = SEGV_BNDERR;
 	info.si_addr  = addr;
 	info.si_lower = lower;
@@ -1755,7 +1740,6 @@ int force_sig_pkuerr(void __user *addr, u32 pkey)
 
 	clear_siginfo(&info);
 	info.si_signo = SIGSEGV;
-	info.si_errno = 0;
 	info.si_code  = SEGV_PKUERR;
 	info.si_addr  = addr;
 	info.si_pkey  = pkey;
@@ -1934,7 +1918,6 @@ bool do_notify_parent(struct task_struct *tsk, int sig)
 
 	clear_siginfo(&info);
 	info.si_signo = sig;
-	info.si_errno = 0;
 	/*
 	 * We are under tasklist_lock here so our parent is tied to
 	 * us and cannot change.
@@ -2033,7 +2016,6 @@ static void do_notify_parent_cldstop(struct task_struct *tsk,
 
 	clear_siginfo(&info);
 	info.si_signo = SIGCHLD;
-	info.si_errno = 0;
 	/*
 	 * see comment in do_notify_parent() about the following 4 lines
 	 */
@@ -2506,7 +2488,6 @@ static int ptrace_signal(int signr, kernel_siginfo_t *info)
 	if (signr != info->si_signo) {
 		clear_siginfo(info);
 		info->si_signo = signr;
-		info->si_errno = 0;
 		info->si_code = SI_USER;
 		rcu_read_lock();
 		info->si_pid = task_pid_vnr(current->parent);
@@ -3660,7 +3641,6 @@ static inline void prepare_kill_siginfo(int sig, struct kernel_siginfo *info)
 {
 	clear_siginfo(info);
 	info->si_signo = sig;
-	info->si_errno = 0;
 	info->si_code = SI_USER;
 	info->si_pid = task_tgid_vnr(current);
 	info->si_uid = from_kuid_munged(current_user_ns(), current_uid());
@@ -3833,7 +3813,6 @@ static int do_tkill(pid_t tgid, pid_t pid, int sig)
 
 	clear_siginfo(&info);
 	info.si_signo = sig;
-	info.si_errno = 0;
 	info.si_code = SI_TKILL;
 	info.si_pid = task_tgid_vnr(current);
 	info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
-- 
2.26.2