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Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org, asantostc@gmail.com, efault@gmx.de, gustavold@gmail.com, calvin@wbinvd.org, jv@jvosburgh.net, kernel-team@meta.com X-Mailer: b4 0.15-dev-47773 X-Developer-Signature: v=1; a=openpgp-sha256; l=5192; i=leitao@debian.org; h=from:subject:message-id; bh=LPqPvdo4ubuN2gY32YVboTIPFg+DFP6SqSHcJnYrbP0=; b=owEBbQKS/ZANAwAIATWjk5/8eHdtAcsmYgBpSVsqHldtZsxTcwW9WAZQteQM0bthqPfP3utOD 9Rakwk28ceJAjMEAAEIAB0WIQSshTmm6PRnAspKQ5s1o5Of/Hh3bQUCaUlbKgAKCRA1o5Of/Hh3 bRCwD/9l4csHXY05KVUulWnq35BblnQOEAG5Fuj2+I9FgmwAIdjspYhsPpsy5g6Uy+IqKlvYJDl y4h/VmEhgc6rm72FIkEgggj000lBNmZrAMPgxob2usOQDx1lnOx3/ROnbZ24gN1alQ/OPgg6FVu 6O6gdEiBd3NnWwZr5wUmHLKbD6sfXclLLiE/rVwbgu9RxIMlEuqjmfKKORA7xiP/rx6UGuowaOx ywPBT77BrhEC1yEJIRjTN2MfZMM8fiRbjd33bB+vdUzZFep2XT3Cmb7i12pV1PavvkRvio3KznS d+7ZA0AptlHCAGMfRUJlmniFRVusTnXVCwoaqg7GhWkbZ9sRy1dqwg6O8qw0YX/t8lPxkzN2dUg Lj09lg6wVUo3IxIe7B2d9PYX1gS8a07m3zzGgrlPOKYAuWqvnYiNS+2vx2jv04d+bx4MxtvtNqC KsADQyqB6en9R1fCfAbCCQAdnEGPT5ng89vKqr4i/FAPgnES52B7kbo7+/ix+Jtnkf0+nW3MZBf ZeZEfN8JJoSmCNGGqLGQGEk9TzNceJyUhJCcl6eTDb2w0Jg9PDUtuiBEtQOmgcbJyGNkTQ6TFPy Opb90gPOtkz+l2gjMjbmwsVLfLOOcqtxA/wuRjpdxFlPVVtqldhxP9Uns4XnPdpedGnR+cJrFKI 33L23AGiyww4Crg== 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 - Set write_thread and write_atomic callbacks (both use same function) Link: https://lore.kernel.org/all/b2qps3uywhmjaym4mht2wpxul4yqtuuayeoq4iv4k= 3zf5wdgh3@tocu6c7mj4lt/ [1] Signed-off-by: Breno Leitao --- drivers/net/netconsole.c | 95 +++++++++++++++++++++++++++++---------------= ---- 1 file changed, 58 insertions(+), 37 deletions(-) diff --git a/drivers/net/netconsole.c b/drivers/net/netconsole.c index dc3bd7c9b049..248b401bcaa4 100644 --- a/drivers/net/netconsole.c +++ b/drivers/net/netconsole.c @@ -1709,22 +1709,6 @@ static void send_ext_msg_udp(struct netconsole_targe= t *nt, const char *msg, sysdata_len); } =20 -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 +1723,60 @@ static void send_msg_udp(struct netconsole_target *= nt, const char *msg, } } =20 -static void write_msg(struct console *con, const char *msg, unsigned int l= en) +/** + * netconsole_write - Generic function to send a msg to all targets + * @wctxt: nbcon write context + * @extended: "true" for extended console mode + * + * Given a 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; =20 if (oops_only && !oops_in_progress) return; - /* Avoid taking lock and disabling interrupts unnecessarily */ - if (list_empty(&target_list)) - return; =20 - 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 !=3D extended || !nt->enabled || + !netif_running(nt->np.dev)) + continue; + + if (!nbcon_enter_unsafe(wctxt)) + continue; + + 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); } =20 @@ -1924,15 +1939,21 @@ static void free_param_target(struct netconsole_tar= get *nt) } =20 static struct console netconsole_ext =3D { - .name =3D "netcon_ext", - .flags =3D CON_ENABLED | CON_EXTENDED, - .write =3D write_ext_msg, + .name =3D "netcon_ext", + .flags =3D CON_ENABLED | CON_EXTENDED | CON_NBCON | CON_NBCON_ATOMIC_UNSA= FE, + .write_thread =3D netconsole_write_ext, + .write_atomic =3D netconsole_write_ext, + .device_lock =3D netconsole_device_lock, + .device_unlock =3D netconsole_device_unlock, }; =20 static struct console netconsole =3D { - .name =3D "netcon", - .flags =3D CON_ENABLED, - .write =3D write_msg, + .name =3D "netcon", + .flags =3D CON_ENABLED | CON_NBCON | CON_NBCON_ATOMIC_UNSAFE, + .write_thread =3D netconsole_write_basic, + .write_atomic =3D netconsole_write_basic, + .device_lock =3D netconsole_device_lock, + .device_unlock =3D netconsole_device_unlock, }; =20 static int __init init_netconsole(void) --=20 2.47.3