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Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , pmladek@suse.com, john.ogness@linutronix.de Cc: Greg Kroah-Hartman , Steven Rostedt , Sergey Senozhatsky , Andrew Morton , netdev@vger.kernel.org, linux-kernel@vger.kernel.org, asantostc@gmail.com, efault@gmx.de, gustavold@gmail.com, calvin@wbinvd.org, jv@jvosburgh.net, mpdesouza@suse.com, kernel-team@meta.com X-Mailer: b4 0.15-dev-47773 X-Developer-Signature: v=1; a=openpgp-sha256; l=5459; i=leitao@debian.org; h=from:subject:message-id; bh=URguZv+z+GzFNe+cJ2zMPSHRjgwbLnOTJ/PrC+X4qs0=; b=owEBbQKS/ZANAwAIATWjk5/8eHdtAcsmYgBpcgrNnBzlq2sCqvYqNWopVniZXZwhF+EAy0FZt /lJur4VjiOJAjMEAAEIAB0WIQSshTmm6PRnAspKQ5s1o5Of/Hh3bQUCaXIKzQAKCRA1o5Of/Hh3 bQgrD/9LJPolJfqcMzc7xid17bEvJo25PdG3c6+kGt1qwOXC596udfOZRcEhn5Qm14JVzbejD/g JQM3P1aflYOCJSiKSA8E4GQGCz3w5zEmhu0vDF1fetEEuY3AFqJmHpWpbSQAV0n60e5Wa/BZ6DL pfDjWYOcio/XpOaikwdd6W23F9pGt4FZxdeFoVvL308VVVFlr6KYkztaeHLsQ7dVVoHortUfKEs KUw/zU0hEtJrI8l7sfpwNy6SrnJWat/a/EkrIgYLoCKG92Z2OMsFekAnTEMbegfn8+C6vGKrrFE Pr82pHiZ0xAl7xOalemmNEvQWKRcBxqqbKIRvqFgJDd8Ls/rarknuZabBZeDmLdzWyJMZDCl8yW TLPcvLLvmTmlhahIGHEb951aTQhAuABOpbUtyPQveo1r3ZdwnXbr3NmS3J3hSgCwlVzzjfQGd6r aCRpz5Y8AzTTkIWuOhQmkA/0s7Z94xneWMOfVODD6IuRAGzTKAJim3vxxEH9hlJf9Z1dEuYXc5a qBszkoW+U7p+m0c+QwkwQLMKQxmliwEuzL8EeCZ3XTukqwVONOrUspivL0PRoBVyDEmA59q7DCW cPFRjO7idJ5X9PgPHq8BulGvM8+5e+pB+e0OsKzv4YRBXs443VgdE7XUlTwuyn4YjqF1/FDQs4a U6JlsStVydjYXXQ== X-Developer-Key: i=leitao@debian.org; a=openpgp; fpr=AC8539A6E8F46702CA4A439B35A3939FFC78776D Convert netconsole from the legacy console API to the NBCON framework. NBCON provides threaded printing which unblocks printk()s and flushes in a thread, decoupling network TX from printk() when netconsole is in use. Since netconsole relies on the network stack which cannot safely operate from all atomic contexts, mark both consoles with CON_NBCON_ATOMIC_UNSAFE. (See discussion in [1]) CON_NBCON_ATOMIC_UNSAFE restricts write_atomic() usage to emergency scenarios (panic) where regular messages are sent in threaded mode. Implementation changes: - Unify write_ext_msg() and write_msg() into netconsole_write() - Add device_lock/device_unlock callbacks to manage target_list_lock - Use nbcon_enter_unsafe()/nbcon_exit_unsafe() around network operations. - If nbcon_enter_unsafe() fails, just return given netconsole lost the ownership of the console. - Set write_thread and write_atomic callbacks (both use same function) Link: https://lore.kernel.org/all/b2qps3uywhmjaym4mht2wpxul4yqtuuayeoq4iv4k3zf5wdgh3@tocu6c7mj4lt/ [1] Signed-off-by: Breno Leitao --- drivers/net/netconsole.c | 97 ++++++++++++++++++++++++++++++------------------ 1 file changed, 60 insertions(+), 37 deletions(-) diff --git a/drivers/net/netconsole.c b/drivers/net/netconsole.c index dc3bd7c9b0498..c5d7e97fe2a78 100644 --- a/drivers/net/netconsole.c +++ b/drivers/net/netconsole.c @@ -1709,22 +1709,6 @@ static void send_ext_msg_udp(struct netconsole_target *nt, const char *msg, sysdata_len); } -static void write_ext_msg(struct console *con, const char *msg, - unsigned int len) -{ - struct netconsole_target *nt; - unsigned long flags; - - if ((oops_only && !oops_in_progress) || list_empty(&target_list)) - return; - - spin_lock_irqsave(&target_list_lock, flags); - list_for_each_entry(nt, &target_list, list) - if (nt->extended && nt->enabled && netif_running(nt->np.dev)) - send_ext_msg_udp(nt, msg, len); - spin_unlock_irqrestore(&target_list_lock, flags); -} - static void send_msg_udp(struct netconsole_target *nt, const char *msg, unsigned int len) { @@ -1739,29 +1723,62 @@ static void send_msg_udp(struct netconsole_target *nt, const char *msg, } } -static void write_msg(struct console *con, const char *msg, unsigned int len) +/** + * netconsole_write - Generic function to send a msg to all targets + * @wctxt: nbcon write context + * @extended: "true" for extended console mode + * + * Given an nbcon write context, send the message to the netconsole targets + */ +static void netconsole_write(struct nbcon_write_context *wctxt, bool extended) { - unsigned long flags; struct netconsole_target *nt; if (oops_only && !oops_in_progress) return; - /* Avoid taking lock and disabling interrupts unnecessarily */ - if (list_empty(&target_list)) - return; - spin_lock_irqsave(&target_list_lock, flags); list_for_each_entry(nt, &target_list, list) { - if (!nt->extended && nt->enabled && netif_running(nt->np.dev)) { - /* - * We nest this inside the for-each-target loop above - * so that we're able to get as much logging out to - * at least one target if we die inside here, instead - * of unnecessarily keeping all targets in lock-step. - */ - send_msg_udp(nt, msg, len); - } + if (nt->extended != extended || !nt->enabled || + !netif_running(nt->np.dev)) + continue; + + /* If nbcon_enter_unsafe() fails, just return given netconsole + * lost the ownership, and iterating over the targets will not + * be able to re-acquire. + */ + if (!nbcon_enter_unsafe(wctxt)) + return; + + if (extended) + send_ext_msg_udp(nt, wctxt->outbuf, wctxt->len); + else + send_msg_udp(nt, wctxt->outbuf, wctxt->len); + + nbcon_exit_unsafe(wctxt); } +} + +static void netconsole_write_ext(struct console *con __always_unused, + struct nbcon_write_context *wctxt) +{ + netconsole_write(wctxt, true); +} + +static void netconsole_write_basic(struct console *con __always_unused, + struct nbcon_write_context *wctxt) +{ + netconsole_write(wctxt, false); +} + +static void netconsole_device_lock(struct console *con __always_unused, + unsigned long *flags) +{ + spin_lock_irqsave(&target_list_lock, *flags); +} + +static void netconsole_device_unlock(struct console *con __always_unused, + unsigned long flags) +{ spin_unlock_irqrestore(&target_list_lock, flags); } @@ -1924,15 +1941,21 @@ static void free_param_target(struct netconsole_target *nt) } static struct console netconsole_ext = { - .name = "netcon_ext", - .flags = CON_ENABLED | CON_EXTENDED, - .write = write_ext_msg, + .name = "netcon_ext", + .flags = CON_ENABLED | CON_EXTENDED | CON_NBCON | CON_NBCON_ATOMIC_UNSAFE, + .write_thread = netconsole_write_ext, + .write_atomic = netconsole_write_ext, + .device_lock = netconsole_device_lock, + .device_unlock = netconsole_device_unlock, }; static struct console netconsole = { - .name = "netcon", - .flags = CON_ENABLED, - .write = write_msg, + .name = "netcon", + .flags = CON_ENABLED | CON_NBCON | CON_NBCON_ATOMIC_UNSAFE, + .write_thread = netconsole_write_basic, + .write_atomic = netconsole_write_basic, + .device_lock = netconsole_device_lock, + .device_unlock = netconsole_device_unlock, }; static int __init init_netconsole(void) -- 2.47.3