The threaded ISR handlers (thunderx_ocx_com_threaded_isr(),
thunderx_ocx_lnk_threaded_isr(), and thunderx_l2c_threaded_isr()) build
multi-line error reports by formatting register details into a scratch
buffer and appending them to "msg" with strlcat().

In preparation for removing the deprecated strlcat() API[1], refactor the
ISR handlers to construct error messages using struct seq_buf.

Additionally, fix two bugs in decode_register(): initialize "str[0] = '\0'"
so callers do not append stale buffer contents when no error bits match,
and stop iterating if snprintf() truncates the buffer to avoid
underflowing the remaining "size" counter.

Link: https://github.com/KSPP/linux/issues/370 [1]
Cc: [email protected]
Assisted-by: AI:Claude-3-5-Sonnet [editor_update_file, shell_command_run]
Signed-off-by: Bill Wendling <[email protected]>
---
Cc: Russell King <[email protected]>
Cc: Huacai Chen <[email protected]>
Cc: WANG Xuerui <[email protected]>
Cc: Thomas Bogendoerfer <[email protected]>
Cc: "James E.J. Bottomley" <[email protected]>
Cc: Helge Deller <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: [email protected]
Cc: "H. Peter Anvin" <[email protected]>
Cc: Ian Abbott <[email protected]>
Cc: H Hartley Sweeten <[email protected]>
Cc: Tony Luck <[email protected]>
Cc: Maarten Lankhorst <[email protected]>
Cc: Maxime Ripard <[email protected]>
Cc: Thomas Zimmermann <[email protected]>
Cc: David Airlie <[email protected]>
Cc: Simona Vetter <[email protected]>
Cc: Matthew Brost <[email protected]>
Cc: "Thomas Hellström" <[email protected]>
Cc: Rodrigo Vivi <[email protected]>
Cc: Dmitry Torokhov <[email protected]>
Cc: Matthias Schwarzott <[email protected]>
Cc: Mauro Carvalho Chehab <[email protected]>
Cc: Tony Nguyen <[email protected]>
Cc: Przemek Kitszel <[email protected]>
Cc: Andrew Lunn <[email protected]>
Cc: "David S. Miller" <[email protected]>
Cc: Eric Dumazet <[email protected]>
Cc: Jakub Kicinski <[email protected]>
Cc: Paolo Abeni <[email protected]>
Cc: Arend van Spriel <[email protected]>
Cc: Rob Herring <[email protected]>
Cc: Saravana Kannan <[email protected]>
Cc: Krzysztof Kozlowski <[email protected]>
Cc: Sylwester Nawrocki <[email protected]>
Cc: Peter Griffin <[email protected]>
Cc: Alim Akhtar <[email protected]>
Cc: Linus Walleij <[email protected]>
Cc: Anil Gurumurthy <[email protected]>
Cc: Sudarsana Kalluru <[email protected]>
Cc: "Martin K. Petersen" <[email protected]>
Cc: Trond Myklebust <[email protected]>
Cc: Anna Schumaker <[email protected]>
Cc: Mike Marshall <[email protected]>
Cc: Martin Brandenburg <[email protected]>
Cc: Kees Cook <[email protected]>
Cc: Jiri Pirko <[email protected]>
Cc: Simon Horman <[email protected]>
Cc: Chuck Lever <[email protected]>
Cc: Jeff Layton <[email protected]>
Cc: NeilBrown <[email protected]>
Cc: Olga Kornievskaia <[email protected]>
Cc: Dai Ngo <[email protected]>
Cc: Tom Talpey <[email protected]>
Cc: Jaroslav Kysela <[email protected]>
Cc: Takashi Iwai <[email protected]>
Cc: Bill Wendling <[email protected]>
Cc: Andrew Morton <[email protected]>
Cc: "Mike Rapoport (Microsoft)" <[email protected]>
Cc: Kanglong Wang <[email protected]>
Cc: Tiezhu Yang <[email protected]>
Cc: Qiang Ma <[email protected]>
Cc: Randy Dunlap <[email protected]>
Cc: Pengpeng Hou <[email protected]>
Cc: Ard Biesheuvel <[email protected]>
Cc: Breno Leitao <[email protected]>
Cc: Thorsten Blum <[email protected]>
Cc: Harshit Mogalapalli <[email protected]>
Cc: Greg Kroah-Hartman <[email protected]>
Cc: Lyude Paul <[email protected]>
Cc: Ashutosh Desai <[email protected]>
Cc: Imre Deak <[email protected]>
Cc: Dmitry Baryshkov <[email protected]>
Cc: Johan Hovold <[email protected]>
Cc: Johannes Berg <[email protected]>
Cc: Miri Korenblit <[email protected]>
Cc: Alexander Stein <[email protected]>
Cc: Cryolitia PukNgae <[email protected]>
Cc: Jiaming Zhang <[email protected]>
Cc: Will Porter <[email protected]>
Cc: Cen Zhang <[email protected]>
Cc: "Cássio Gabriel" <[email protected]>
Cc: Rong Zhang <[email protected]>
Cc: Arun Raghavan <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
---
 drivers/edac/thunderx_edac.c | 64 ++++++++++++++++++++++--------------
 1 file changed, 39 insertions(+), 25 deletions(-)

diff --git a/drivers/edac/thunderx_edac.c b/drivers/edac/thunderx_edac.c
index e7c335ca0c36..4e3781815b6d 100644
--- a/drivers/edac/thunderx_edac.c
+++ b/drivers/edac/thunderx_edac.c
@@ -20,6 +20,7 @@
 #include <linux/atomic.h>
 #include <linux/bitfield.h>
 #include <linux/circ_buf.h>
+#include <linux/seq_buf.h>
 
 #include <asm/page.h>
 
@@ -47,12 +48,17 @@ static void decode_register(char *str, size_t size,
 {
        int ret = 0;
 
+       if (size > 0)
+               str[0] = '\0';
+
        while (descr->type && descr->mask && descr->descr) {
                if (reg & descr->mask) {
                        ret = snprintf(str, size, "\n\t%s, %s",
                                       descr->type == ERR_CORRECTED ?
                                         "Corrected" : "Uncorrected",
                                       descr->descr);
+                       if (ret < 0 || ret >= size)
+                               break;
                        str += ret;
                        size -= ret;
                }
@@ -1115,35 +1121,37 @@ static irqreturn_t thunderx_ocx_com_threaded_isr(int 
irq, void *irq_id)
 
        while (CIRC_CNT(ocx->com_ring_head, ocx->com_ring_tail,
                        ARRAY_SIZE(ocx->com_err_ctx))) {
+               struct seq_buf s;
+
                tail = ring_pos(ocx->com_ring_tail,
                                ARRAY_SIZE(ocx->com_err_ctx));
                ctx = &ocx->com_err_ctx[tail];
 
-               snprintf(msg, OCX_MESSAGE_SIZE, "%s: OCX_COM_INT: %016llx",
-                       ocx->edac_dev->ctl_name, ctx->reg_com_int);
+               seq_buf_init(&s, msg, OCX_MESSAGE_SIZE);
+
+               seq_buf_printf(&s, "%s: OCX_COM_INT: %016llx",
+                              ocx->edac_dev->ctl_name, ctx->reg_com_int);
 
                decode_register(other, OCX_OTHER_SIZE,
                                ocx_com_errors, ctx->reg_com_int);
 
-               strlcat(msg, other, OCX_MESSAGE_SIZE);
+               seq_buf_puts(&s, other);
 
                for (lane = 0; lane < OCX_RX_LANES; lane++)
                        if (ctx->reg_com_int & BIT(lane)) {
-                               snprintf(other, OCX_OTHER_SIZE,
-                                        "\n\tOCX_LNE_INT[%02d]: %016llx 
OCX_LNE_STAT11[%02d]: %016llx",
-                                        lane, ctx->reg_lane_int[lane],
-                                        lane, ctx->reg_lane_stat11[lane]);
-
-                               strlcat(msg, other, OCX_MESSAGE_SIZE);
+                               seq_buf_printf(&s,
+                                              "\n\tOCX_LNE_INT[%02d]: %016llx 
OCX_LNE_STAT11[%02d]: %016llx",
+                                              lane, ctx->reg_lane_int[lane],
+                                              lane, 
ctx->reg_lane_stat11[lane]);
 
                                decode_register(other, OCX_OTHER_SIZE,
                                                ocx_lane_errors,
                                                ctx->reg_lane_int[lane]);
-                               strlcat(msg, other, OCX_MESSAGE_SIZE);
+                               seq_buf_puts(&s, other);
                        }
 
                if (ctx->reg_com_int & OCX_COM_INT_CE)
-                       edac_device_handle_ce(ocx->edac_dev, 0, 0, msg);
+                       edac_device_handle_ce(ocx->edac_dev, 0, 0, 
seq_buf_str(&s));
 
                ocx->com_ring_tail++;
        }
@@ -1196,25 +1204,28 @@ static irqreturn_t thunderx_ocx_lnk_threaded_isr(int 
irq, void *irq_id)
 
        while (CIRC_CNT(ocx->link_ring_head, ocx->link_ring_tail,
                        ARRAY_SIZE(ocx->link_err_ctx))) {
+               struct seq_buf s;
+
                tail = ring_pos(ocx->link_ring_head,
                                ARRAY_SIZE(ocx->link_err_ctx));
 
                ctx = &ocx->link_err_ctx[tail];
 
-               snprintf(msg, OCX_MESSAGE_SIZE,
-                        "%s: OCX_COM_LINK_INT[%d]: %016llx",
-                        ocx->edac_dev->ctl_name,
-                        ctx->link, ctx->reg_com_link_int);
+               seq_buf_init(&s, msg, OCX_MESSAGE_SIZE);
+
+               seq_buf_printf(&s, "%s: OCX_COM_LINK_INT[%d]: %016llx",
+                              ocx->edac_dev->ctl_name,
+                              ctx->link, ctx->reg_com_link_int);
 
                decode_register(other, OCX_OTHER_SIZE,
                                ocx_com_link_errors, ctx->reg_com_link_int);
 
-               strlcat(msg, other, OCX_MESSAGE_SIZE);
+               seq_buf_puts(&s, other);
 
                if (ctx->reg_com_link_int & OCX_COM_LINK_INT_UE)
-                       edac_device_handle_ue(ocx->edac_dev, 0, 0, msg);
+                       edac_device_handle_ue(ocx->edac_dev, 0, 0, 
seq_buf_str(&s));
                else if (ctx->reg_com_link_int & OCX_COM_LINK_INT_CE)
-                       edac_device_handle_ce(ocx->edac_dev, 0, 0, msg);
+                       edac_device_handle_ce(ocx->edac_dev, 0, 0, 
seq_buf_str(&s));
 
                ocx->link_ring_tail++;
        }
@@ -1880,22 +1891,25 @@ static irqreturn_t thunderx_l2c_threaded_isr(int irq, 
void *irq_id)
 
        while (CIRC_CNT(l2c->ring_head, l2c->ring_tail,
                        ARRAY_SIZE(l2c->err_ctx))) {
+               struct seq_buf s;
+
                tail = ring_pos(l2c->ring_tail, ARRAY_SIZE(l2c->err_ctx));
                ctx = &l2c->err_ctx[tail];
 
-               snprintf(msg, L2C_MESSAGE_SIZE,
-                        "%s: %s: %016llx, %s: %016llx",
-                        l2c->edac_dev->ctl_name, reg_int_name, ctx->reg_int,
-                        ctx->reg_ext_name, ctx->reg_ext);
+               seq_buf_init(&s, msg, L2C_MESSAGE_SIZE);
+
+               seq_buf_printf(&s, "%s: %s: %016llx, %s: %016llx",
+                              l2c->edac_dev->ctl_name, reg_int_name, 
ctx->reg_int,
+                              ctx->reg_ext_name, ctx->reg_ext);
 
                decode_register(other, L2C_OTHER_SIZE, l2_errors, ctx->reg_int);
 
-               strlcat(msg, other, L2C_MESSAGE_SIZE);
+               seq_buf_puts(&s, other);
 
                if (ctx->reg_int & mask_ue)
-                       edac_device_handle_ue(l2c->edac_dev, 0, 0, msg);
+                       edac_device_handle_ue(l2c->edac_dev, 0, 0, 
seq_buf_str(&s));
                else if (ctx->reg_int & mask_ce)
-                       edac_device_handle_ce(l2c->edac_dev, 0, 0, msg);
+                       edac_device_handle_ce(l2c->edac_dev, 0, 0, 
seq_buf_str(&s));
 
                l2c->ring_tail++;
        }
-- 
2.55.0.1032.g73a4cd73de-goog

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