[PATCH] Revert "media: siano: Convert to use sysfs_emit_at() API"

[Alessandro Menezes]

This reverts commit 2f7d0c94396e ("media: siano: Convert to use
sysfs_emit_at() API").

sysfs_emit_at() may only be used from sysfs show() methods, where the
destination is the page-sized, page-aligned buffer that sysfs passes to
the callback.  It enforces that at runtime:

	if (WARN(!buf || offset_in_page(buf) || at < 0 || at >= PAGE_SIZE,
		 "invalid sysfs_emit_at: buf:%p at:%d\n", buf, at))
		return 0;

smsdvb has no show() method.  The converted functions format statistics
into smsdvb_debugfs.stats_data, a plain char[PAGE_SIZE] member of a
kmalloc()'d struct, which reaches userspace through debugfs via
simple_read_from_buffer().  The preceding kref and spinlock_t place
stats_data at offset 8 in the object, and the object itself is 4136
bytes, so it is served from the kmalloc-8192 cache with a page-aligned
base.  offset_in_page(stats_data) is therefore always 8, never 0, and
every one of the 104 converted calls trips the WARN and returns 0
without writing anything:

  WARNING: fs/sysfs/file.c:781 at sysfs_emit_at+0x59/0xd0
  invalid sysfs_emit_at: buf:00000000fb2f86e6 at:0
   smsdvb_print_isdb_stats_ex+0x459/0x650 [smsdvb]
   smsdvb_update_isdbt_stats_ex+0x34/0x6e0 [smsdvb]
   smsdvb_onresponse+0x2bc/0x6a0 [smsdvb]
   smsusb_onresponse+0x117/0x230 [smsusb]

The statistics are formatted from the USB completion handler, so this
fires from interrupt context on every statistics response the device
sends, and the debugfs stats file is permanently empty.

Note the buffer cannot be realigned the way commit 8f48ba303dfb
("drm/amdgpu: fix sysfs_emit/sysfs_emit_at warnings(v2)") handled the
same warning: there the buffer really was a sysfs page that had been
advanced past its start, so walking back to the page boundary was valid.
Here it is not a page at all, and backing the pointer up by
offset_in_page() would land on the struct's own kref and spinlock.

scnprintf() is the correct interface for formatting into a
driver-private buffer, and was the deliberate choice here since commit
af72bc8cd6ab ("media: siano: Use scnprintf() for avoiding potential
buffer overflow").

Fixes: 2f7d0c94396e ("media: siano: Convert to use sysfs_emit_at() API")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Alessandro Menezes <alessandroasm@xxxxxxxxx>
---
Tested on 7.0.0-30-generic with a Siano MDTV receiver (USB 187f:0600,
ISDB-T).  Before: reading
/sys/kernel/debug/usb/smsdvb/<dev>/stats returns nothing and each
statistics response from the device adds a WARN.  After: the file
contains the full per-layer ISDB-T statistics and no WARN is logged.

offsetof()/sizeof() above were measured on that kernel, not inferred.

--- a/drivers/media/common/siano/smsdvb-debugfs.c
+++ b/drivers/media/common/siano/smsdvb-debugfs.c
@@ -45,48 +45,89 @@
 
 	buf = debug_data->stats_data;
 
-	n += sysfs_emit_at(buf, n, "is_rf_locked = %d\n", p->is_rf_locked);
-	n += sysfs_emit_at(buf, n, "is_demod_locked = %d\n", p->is_demod_locked);
-	n += sysfs_emit_at(buf, n, "is_external_lna_on = %d\n", p->is_external_lna_on);
-	n += sysfs_emit_at(buf, n, "SNR = %d\n", p->SNR);
-	n += sysfs_emit_at(buf, n, "ber = %d\n", p->ber);
-	n += sysfs_emit_at(buf, n, "FIB_CRC = %d\n", p->FIB_CRC);
-	n += sysfs_emit_at(buf, n, "ts_per = %d\n", p->ts_per);
-	n += sysfs_emit_at(buf, n, "MFER = %d\n", p->MFER);
-	n += sysfs_emit_at(buf, n, "RSSI = %d\n", p->RSSI);
-	n += sysfs_emit_at(buf, n, "in_band_pwr = %d\n", p->in_band_pwr);
-	n += sysfs_emit_at(buf, n, "carrier_offset = %d\n", p->carrier_offset);
-	n += sysfs_emit_at(buf, n, "modem_state = %d\n", p->modem_state);
-	n += sysfs_emit_at(buf, n, "frequency = %d\n", p->frequency);
-	n += sysfs_emit_at(buf, n, "bandwidth = %d\n", p->bandwidth);
-	n += sysfs_emit_at(buf, n, "transmission_mode = %d\n", p->transmission_mode);
-	n += sysfs_emit_at(buf, n, "modem_state = %d\n", p->modem_state);
-	n += sysfs_emit_at(buf, n, "guard_interval = %d\n", p->guard_interval);
-	n += sysfs_emit_at(buf, n, "code_rate = %d\n", p->code_rate);
-	n += sysfs_emit_at(buf, n, "lp_code_rate = %d\n", p->lp_code_rate);
-	n += sysfs_emit_at(buf, n, "hierarchy = %d\n", p->hierarchy);
-	n += sysfs_emit_at(buf, n, "constellation = %d\n", p->constellation);
-	n += sysfs_emit_at(buf, n, "burst_size = %d\n", p->burst_size);
-	n += sysfs_emit_at(buf, n, "burst_duration = %d\n", p->burst_duration);
-	n += sysfs_emit_at(buf, n, "burst_cycle_time = %d\n", p->burst_cycle_time);
-	n += sysfs_emit_at(buf, n, "calc_burst_cycle_time = %d\n", p->calc_burst_cycle_time);
-	n += sysfs_emit_at(buf, n, "num_of_rows = %d\n", p->num_of_rows);
-	n += sysfs_emit_at(buf, n, "num_of_padd_cols = %d\n", p->num_of_padd_cols);
-	n += sysfs_emit_at(buf, n, "num_of_punct_cols = %d\n", p->num_of_punct_cols);
-	n += sysfs_emit_at(buf, n, "error_ts_packets = %d\n", p->error_ts_packets);
-	n += sysfs_emit_at(buf, n, "total_ts_packets = %d\n", p->total_ts_packets);
-	n += sysfs_emit_at(buf, n, "num_of_valid_mpe_tlbs = %d\n", p->num_of_valid_mpe_tlbs);
-	n += sysfs_emit_at(buf, n, "num_of_invalid_mpe_tlbs = %d\n", p->num_of_invalid_mpe_tlbs);
-	n += sysfs_emit_at(buf, n, "num_of_corrected_mpe_tlbs = %d\n",
-			   p->num_of_corrected_mpe_tlbs);
-	n += sysfs_emit_at(buf, n, "ber_error_count = %d\n", p->ber_error_count);
-	n += sysfs_emit_at(buf, n, "ber_bit_count = %d\n", p->ber_bit_count);
-	n += sysfs_emit_at(buf, n, "sms_to_host_tx_errors = %d\n", p->sms_to_host_tx_errors);
-	n += sysfs_emit_at(buf, n, "pre_ber = %d\n", p->pre_ber);
-	n += sysfs_emit_at(buf, n, "cell_id = %d\n", p->cell_id);
-	n += sysfs_emit_at(buf, n, "dvbh_srv_ind_hp = %d\n", p->dvbh_srv_ind_hp);
-	n += sysfs_emit_at(buf, n, "dvbh_srv_ind_lp = %d\n", p->dvbh_srv_ind_lp);
-	n += sysfs_emit_at(buf, n, "num_mpe_received = %d\n", p->num_mpe_received);
+	n += scnprintf(&buf[n], PAGE_SIZE - n,
+		      "is_rf_locked = %d\n", p->is_rf_locked);
+	n += scnprintf(&buf[n], PAGE_SIZE - n,
+		      "is_demod_locked = %d\n", p->is_demod_locked);
+	n += scnprintf(&buf[n], PAGE_SIZE - n,
+		      "is_external_lna_on = %d\n", p->is_external_lna_on);
+	n += scnprintf(&buf[n], PAGE_SIZE - n,
+		      "SNR = %d\n", p->SNR);
+	n += scnprintf(&buf[n], PAGE_SIZE - n,
+		      "ber = %d\n", p->ber);
+	n += scnprintf(&buf[n], PAGE_SIZE - n,
+		      "FIB_CRC = %d\n", p->FIB_CRC);
+	n += scnprintf(&buf[n], PAGE_SIZE - n,
+		      "ts_per = %d\n", p->ts_per);
+	n += scnprintf(&buf[n], PAGE_SIZE - n,
+		      "MFER = %d\n", p->MFER);
+	n += scnprintf(&buf[n], PAGE_SIZE - n,
+		      "RSSI = %d\n", p->RSSI);
+	n += scnprintf(&buf[n], PAGE_SIZE - n,
+		      "in_band_pwr = %d\n", p->in_band_pwr);
+	n += scnprintf(&buf[n], PAGE_SIZE - n,
+		      "carrier_offset = %d\n", p->carrier_offset);
+	n += scnprintf(&buf[n], PAGE_SIZE - n,
+		      "modem_state = %d\n", p->modem_state);
+	n += scnprintf(&buf[n], PAGE_SIZE - n,
+		      "frequency = %d\n", p->frequency);
+	n += scnprintf(&buf[n], PAGE_SIZE - n,
+		      "bandwidth = %d\n", p->bandwidth);
+	n += scnprintf(&buf[n], PAGE_SIZE - n,
+		      "transmission_mode = %d\n", p->transmission_mode);
+	n += scnprintf(&buf[n], PAGE_SIZE - n,
+		      "modem_state = %d\n", p->modem_state);
+	n += scnprintf(&buf[n], PAGE_SIZE - n,
+		      "guard_interval = %d\n", p->guard_interval);
+	n += scnprintf(&buf[n], PAGE_SIZE - n,
+		      "code_rate = %d\n", p->code_rate);
+	n += scnprintf(&buf[n], PAGE_SIZE - n,
+		      "lp_code_rate = %d\n", p->lp_code_rate);
+	n += scnprintf(&buf[n], PAGE_SIZE - n,
+		      "hierarchy = %d\n", p->hierarchy);
+	n += scnprintf(&buf[n], PAGE_SIZE - n,
+		      "constellation = %d\n", p->constellation);
+	n += scnprintf(&buf[n], PAGE_SIZE - n,
+		      "burst_size = %d\n", p->burst_size);
+	n += scnprintf(&buf[n], PAGE_SIZE - n,
+		      "burst_duration = %d\n", p->burst_duration);
+	n += scnprintf(&buf[n], PAGE_SIZE - n,
+		      "burst_cycle_time = %d\n", p->burst_cycle_time);
+	n += scnprintf(&buf[n], PAGE_SIZE - n,
+		      "calc_burst_cycle_time = %d\n",
+		      p->calc_burst_cycle_time);
+	n += scnprintf(&buf[n], PAGE_SIZE - n,
+		      "num_of_rows = %d\n", p->num_of_rows);
+	n += scnprintf(&buf[n], PAGE_SIZE - n,
+		      "num_of_padd_cols = %d\n", p->num_of_padd_cols);
+	n += scnprintf(&buf[n], PAGE_SIZE - n,
+		      "num_of_punct_cols = %d\n", p->num_of_punct_cols);
+	n += scnprintf(&buf[n], PAGE_SIZE - n,
+		      "error_ts_packets = %d\n", p->error_ts_packets);
+	n += scnprintf(&buf[n], PAGE_SIZE - n,
+		      "total_ts_packets = %d\n", p->total_ts_packets);
+	n += scnprintf(&buf[n], PAGE_SIZE - n,
+		      "num_of_valid_mpe_tlbs = %d\n", p->num_of_valid_mpe_tlbs);
+	n += scnprintf(&buf[n], PAGE_SIZE - n,
+		      "num_of_invalid_mpe_tlbs = %d\n", p->num_of_invalid_mpe_tlbs);
+	n += scnprintf(&buf[n], PAGE_SIZE - n,
+		      "num_of_corrected_mpe_tlbs = %d\n", p->num_of_corrected_mpe_tlbs);
+	n += scnprintf(&buf[n], PAGE_SIZE - n,
+		      "ber_error_count = %d\n", p->ber_error_count);
+	n += scnprintf(&buf[n], PAGE_SIZE - n,
+		      "ber_bit_count = %d\n", p->ber_bit_count);
+	n += scnprintf(&buf[n], PAGE_SIZE - n,
+		      "sms_to_host_tx_errors = %d\n", p->sms_to_host_tx_errors);
+	n += scnprintf(&buf[n], PAGE_SIZE - n,
+		      "pre_ber = %d\n", p->pre_ber);
+	n += scnprintf(&buf[n], PAGE_SIZE - n,
+		      "cell_id = %d\n", p->cell_id);
+	n += scnprintf(&buf[n], PAGE_SIZE - n,
+		      "dvbh_srv_ind_hp = %d\n", p->dvbh_srv_ind_hp);
+	n += scnprintf(&buf[n], PAGE_SIZE - n,
+		      "dvbh_srv_ind_lp = %d\n", p->dvbh_srv_ind_lp);
+	n += scnprintf(&buf[n], PAGE_SIZE - n,
+		      "num_mpe_received = %d\n", p->num_mpe_received);
 
 	debug_data->stats_count = n;
 	spin_unlock(&debug_data->lock);
@@ -107,49 +148,78 @@
 
 	buf = debug_data->stats_data;
 
-	n += sysfs_emit_at(buf, n, "statistics_type = %d\t", p->statistics_type);
-	n += sysfs_emit_at(buf, n, "full_size = %d\n", p->full_size);
-
-	n += sysfs_emit_at(buf, n, "is_rf_locked = %d\t\t", p->is_rf_locked);
-	n += sysfs_emit_at(buf, n, "is_demod_locked = %d\t", p->is_demod_locked);
-	n += sysfs_emit_at(buf, n, "is_external_lna_on = %d\n", p->is_external_lna_on);
-	n += sysfs_emit_at(buf, n, "SNR = %d dB\t\t", p->SNR);
-	n += sysfs_emit_at(buf, n, "RSSI = %d dBm\t\t", p->RSSI);
-	n += sysfs_emit_at(buf, n, "in_band_pwr = %d dBm\n", p->in_band_pwr);
-	n += sysfs_emit_at(buf, n, "carrier_offset = %d\t", p->carrier_offset);
-	n += sysfs_emit_at(buf, n, "bandwidth = %d\t\t", p->bandwidth);
-	n += sysfs_emit_at(buf, n, "frequency = %d Hz\n", p->frequency);
-	n += sysfs_emit_at(buf, n, "transmission_mode = %d\t", p->transmission_mode);
-	n += sysfs_emit_at(buf, n, "modem_state = %d\t\t", p->modem_state);
-	n += sysfs_emit_at(buf, n, "guard_interval = %d\n", p->guard_interval);
-	n += sysfs_emit_at(buf, n, "system_type = %d\t\t", p->system_type);
-	n += sysfs_emit_at(buf, n, "partial_reception = %d\t", p->partial_reception);
-	n += sysfs_emit_at(buf, n, "num_of_layers = %d\n", p->num_of_layers);
-	n += sysfs_emit_at(buf, n, "sms_to_host_tx_errors = %d\n", p->sms_to_host_tx_errors);
+	n += scnprintf(&buf[n], PAGE_SIZE - n,
+		      "statistics_type = %d\t", p->statistics_type);
+	n += scnprintf(&buf[n], PAGE_SIZE - n,
+		      "full_size = %d\n", p->full_size);
+
+	n += scnprintf(&buf[n], PAGE_SIZE - n,
+		      "is_rf_locked = %d\t\t", p->is_rf_locked);
+	n += scnprintf(&buf[n], PAGE_SIZE - n,
+		      "is_demod_locked = %d\t", p->is_demod_locked);
+	n += scnprintf(&buf[n], PAGE_SIZE - n,
+		      "is_external_lna_on = %d\n", p->is_external_lna_on);
+	n += scnprintf(&buf[n], PAGE_SIZE - n,
+		      "SNR = %d dB\t\t", p->SNR);
+	n += scnprintf(&buf[n], PAGE_SIZE - n,
+		      "RSSI = %d dBm\t\t", p->RSSI);
+	n += scnprintf(&buf[n], PAGE_SIZE - n,
+		      "in_band_pwr = %d dBm\n", p->in_band_pwr);
+	n += scnprintf(&buf[n], PAGE_SIZE - n,
+		      "carrier_offset = %d\t", p->carrier_offset);
+	n += scnprintf(&buf[n], PAGE_SIZE - n,
+		      "bandwidth = %d\t\t", p->bandwidth);
+	n += scnprintf(&buf[n], PAGE_SIZE - n,
+		      "frequency = %d Hz\n", p->frequency);
+	n += scnprintf(&buf[n], PAGE_SIZE - n,
+		      "transmission_mode = %d\t", p->transmission_mode);
+	n += scnprintf(&buf[n], PAGE_SIZE - n,
+		      "modem_state = %d\t\t", p->modem_state);
+	n += scnprintf(&buf[n], PAGE_SIZE - n,
+		      "guard_interval = %d\n", p->guard_interval);
+	n += scnprintf(&buf[n], PAGE_SIZE - n,
+		      "system_type = %d\t\t", p->system_type);
+	n += scnprintf(&buf[n], PAGE_SIZE - n,
+		      "partial_reception = %d\t", p->partial_reception);
+	n += scnprintf(&buf[n], PAGE_SIZE - n,
+		      "num_of_layers = %d\n", p->num_of_layers);
+	n += scnprintf(&buf[n], PAGE_SIZE - n,
+		      "sms_to_host_tx_errors = %d\n", p->sms_to_host_tx_errors);
 
 	for (i = 0; i < 3; i++) {
 		if (p->layer_info[i].number_of_segments < 1 ||
 		    p->layer_info[i].number_of_segments > 13)
 			continue;
 
-		n += sysfs_emit_at(buf, n, "\nLayer %d\n", i);
-		n += sysfs_emit_at(buf, n, "\tcode_rate = %d\t", p->layer_info[i].code_rate);
-		n += sysfs_emit_at(buf, n, "constellation = %d\n", p->layer_info[i].constellation);
-		n += sysfs_emit_at(buf, n, "\tber = %-5d\t", p->layer_info[i].ber);
-		n += sysfs_emit_at(buf, n, "\tber_error_count = %-5d\t",
-				   p->layer_info[i].ber_error_count);
-		n += sysfs_emit_at(buf, n, "ber_bit_count = %-5d\n",
-				   p->layer_info[i].ber_bit_count);
-		n += sysfs_emit_at(buf, n, "\tpre_ber = %-5d\t", p->layer_info[i].pre_ber);
-		n += sysfs_emit_at(buf, n, "\tts_per = %-5d\n", p->layer_info[i].ts_per);
-		n += sysfs_emit_at(buf, n, "\terror_ts_packets = %-5d\t",
-				   p->layer_info[i].error_ts_packets);
-		n += sysfs_emit_at(buf, n, "total_ts_packets = %-5d\t",
-				   p->layer_info[i].total_ts_packets);
-		n += sysfs_emit_at(buf, n, "ti_ldepth_i = %d\n", p->layer_info[i].ti_ldepth_i);
-		n += sysfs_emit_at(buf, n, "\tnumber_of_segments = %d\t",
-				   p->layer_info[i].number_of_segments);
-		n += sysfs_emit_at(buf, n, "tmcc_errors = %d\n", p->layer_info[i].tmcc_errors);
+		n += scnprintf(&buf[n], PAGE_SIZE - n, "\nLayer %d\n", i);
+		n += scnprintf(&buf[n], PAGE_SIZE - n, "\tcode_rate = %d\t",
+			      p->layer_info[i].code_rate);
+		n += scnprintf(&buf[n], PAGE_SIZE - n, "constellation = %d\n",
+			      p->layer_info[i].constellation);
+		n += scnprintf(&buf[n], PAGE_SIZE - n, "\tber = %-5d\t",
+			      p->layer_info[i].ber);
+		n += scnprintf(&buf[n], PAGE_SIZE - n,
+			      "\tber_error_count = %-5d\t",
+			      p->layer_info[i].ber_error_count);
+		n += scnprintf(&buf[n], PAGE_SIZE - n, "ber_bit_count = %-5d\n",
+			      p->layer_info[i].ber_bit_count);
+		n += scnprintf(&buf[n], PAGE_SIZE - n, "\tpre_ber = %-5d\t",
+			      p->layer_info[i].pre_ber);
+		n += scnprintf(&buf[n], PAGE_SIZE - n, "\tts_per = %-5d\n",
+			      p->layer_info[i].ts_per);
+		n += scnprintf(&buf[n], PAGE_SIZE - n,
+			      "\terror_ts_packets = %-5d\t",
+			      p->layer_info[i].error_ts_packets);
+		n += scnprintf(&buf[n], PAGE_SIZE - n,
+			      "total_ts_packets = %-5d\t",
+			      p->layer_info[i].total_ts_packets);
+		n += scnprintf(&buf[n], PAGE_SIZE - n, "ti_ldepth_i = %d\n",
+			      p->layer_info[i].ti_ldepth_i);
+		n += scnprintf(&buf[n], PAGE_SIZE - n,
+			      "\tnumber_of_segments = %d\t",
+			      p->layer_info[i].number_of_segments);
+		n += scnprintf(&buf[n], PAGE_SIZE - n, "tmcc_errors = %d\n",
+			      p->layer_info[i].tmcc_errors);
 	}
 
 	debug_data->stats_count = n;
@@ -171,50 +241,80 @@
 
 	buf = debug_data->stats_data;
 
-	n += sysfs_emit_at(buf, n, "statistics_type = %d\t", p->statistics_type);
-	n += sysfs_emit_at(buf, n, "full_size = %d\n", p->full_size);
-
-	n += sysfs_emit_at(buf, n, "is_rf_locked = %d\t\t", p->is_rf_locked);
-	n += sysfs_emit_at(buf, n, "is_demod_locked = %d\t", p->is_demod_locked);
-	n += sysfs_emit_at(buf, n, "is_external_lna_on = %d\n", p->is_external_lna_on);
-	n += sysfs_emit_at(buf, n, "SNR = %d dB\t\t", p->SNR);
-	n += sysfs_emit_at(buf, n, "RSSI = %d dBm\t\t", p->RSSI);
-	n += sysfs_emit_at(buf, n, "in_band_pwr = %d dBm\n", p->in_band_pwr);
-	n += sysfs_emit_at(buf, n, "carrier_offset = %d\t", p->carrier_offset);
-	n += sysfs_emit_at(buf, n, "bandwidth = %d\t\t", p->bandwidth);
-	n += sysfs_emit_at(buf, n, "frequency = %d Hz\n", p->frequency);
-	n += sysfs_emit_at(buf, n, "transmission_mode = %d\t", p->transmission_mode);
-	n += sysfs_emit_at(buf, n, "modem_state = %d\t\t", p->modem_state);
-	n += sysfs_emit_at(buf, n, "guard_interval = %d\n", p->guard_interval);
-	n += sysfs_emit_at(buf, n, "system_type = %d\t\t", p->system_type);
-	n += sysfs_emit_at(buf, n, "partial_reception = %d\t", p->partial_reception);
-	n += sysfs_emit_at(buf, n, "num_of_layers = %d\n", p->num_of_layers);
-	n += sysfs_emit_at(buf, n, "segment_number = %d\t", p->segment_number);
-	n += sysfs_emit_at(buf, n, "tune_bw = %d\n", p->tune_bw);
+	n += scnprintf(&buf[n], PAGE_SIZE - n,
+		      "statistics_type = %d\t", p->statistics_type);
+	n += scnprintf(&buf[n], PAGE_SIZE - n,
+		      "full_size = %d\n", p->full_size);
+
+	n += scnprintf(&buf[n], PAGE_SIZE - n,
+		      "is_rf_locked = %d\t\t", p->is_rf_locked);
+	n += scnprintf(&buf[n], PAGE_SIZE - n,
+		      "is_demod_locked = %d\t", p->is_demod_locked);
+	n += scnprintf(&buf[n], PAGE_SIZE - n,
+		      "is_external_lna_on = %d\n", p->is_external_lna_on);
+	n += scnprintf(&buf[n], PAGE_SIZE - n,
+		      "SNR = %d dB\t\t", p->SNR);
+	n += scnprintf(&buf[n], PAGE_SIZE - n,
+		      "RSSI = %d dBm\t\t", p->RSSI);
+	n += scnprintf(&buf[n], PAGE_SIZE - n,
+		      "in_band_pwr = %d dBm\n", p->in_band_pwr);
+	n += scnprintf(&buf[n], PAGE_SIZE - n,
+		      "carrier_offset = %d\t", p->carrier_offset);
+	n += scnprintf(&buf[n], PAGE_SIZE - n,
+		      "bandwidth = %d\t\t", p->bandwidth);
+	n += scnprintf(&buf[n], PAGE_SIZE - n,
+		      "frequency = %d Hz\n", p->frequency);
+	n += scnprintf(&buf[n], PAGE_SIZE - n,
+		      "transmission_mode = %d\t", p->transmission_mode);
+	n += scnprintf(&buf[n], PAGE_SIZE - n,
+		      "modem_state = %d\t\t", p->modem_state);
+	n += scnprintf(&buf[n], PAGE_SIZE - n,
+		      "guard_interval = %d\n", p->guard_interval);
+	n += scnprintf(&buf[n], PAGE_SIZE - n,
+		      "system_type = %d\t\t", p->system_type);
+	n += scnprintf(&buf[n], PAGE_SIZE - n,
+		      "partial_reception = %d\t", p->partial_reception);
+	n += scnprintf(&buf[n], PAGE_SIZE - n,
+		      "num_of_layers = %d\n", p->num_of_layers);
+	n += scnprintf(&buf[n], PAGE_SIZE - n, "segment_number = %d\t",
+		      p->segment_number);
+	n += scnprintf(&buf[n], PAGE_SIZE - n, "tune_bw = %d\n",
+		      p->tune_bw);
 
 	for (i = 0; i < 3; i++) {
 		if (p->layer_info[i].number_of_segments < 1 ||
 		    p->layer_info[i].number_of_segments > 13)
 			continue;
 
-		n += sysfs_emit_at(buf, n, "\nLayer %d\n", i);
-		n += sysfs_emit_at(buf, n, "\tcode_rate = %d\t", p->layer_info[i].code_rate);
-		n += sysfs_emit_at(buf, n, "constellation = %d\n", p->layer_info[i].constellation);
-		n += sysfs_emit_at(buf, n, "\tber = %-5d\t", p->layer_info[i].ber);
-		n += sysfs_emit_at(buf, n, "\tber_error_count = %-5d\t",
-				   p->layer_info[i].ber_error_count);
-		n += sysfs_emit_at(buf, n, "ber_bit_count = %-5d\n",
-				   p->layer_info[i].ber_bit_count);
-		n += sysfs_emit_at(buf, n, "\tpre_ber = %-5d\t", p->layer_info[i].pre_ber);
-		n += sysfs_emit_at(buf, n, "\tts_per = %-5d\n", p->layer_info[i].ts_per);
-		n += sysfs_emit_at(buf, n, "\terror_ts_packets = %-5d\t",
-				   p->layer_info[i].error_ts_packets);
-		n += sysfs_emit_at(buf, n, "total_ts_packets = %-5d\t",
-				   p->layer_info[i].total_ts_packets);
-		n += sysfs_emit_at(buf, n, "ti_ldepth_i = %d\n", p->layer_info[i].ti_ldepth_i);
-		n += sysfs_emit_at(buf, n, "\tnumber_of_segments = %d\t",
-				   p->layer_info[i].number_of_segments);
-		n += sysfs_emit_at(buf, n, "tmcc_errors = %d\n", p->layer_info[i].tmcc_errors);
+		n += scnprintf(&buf[n], PAGE_SIZE - n, "\nLayer %d\n", i);
+		n += scnprintf(&buf[n], PAGE_SIZE - n, "\tcode_rate = %d\t",
+			      p->layer_info[i].code_rate);
+		n += scnprintf(&buf[n], PAGE_SIZE - n, "constellation = %d\n",
+			      p->layer_info[i].constellation);
+		n += scnprintf(&buf[n], PAGE_SIZE - n, "\tber = %-5d\t",
+			      p->layer_info[i].ber);
+		n += scnprintf(&buf[n], PAGE_SIZE - n,
+			      "\tber_error_count = %-5d\t",
+			      p->layer_info[i].ber_error_count);
+		n += scnprintf(&buf[n], PAGE_SIZE - n, "ber_bit_count = %-5d\n",
+			      p->layer_info[i].ber_bit_count);
+		n += scnprintf(&buf[n], PAGE_SIZE - n, "\tpre_ber = %-5d\t",
+			      p->layer_info[i].pre_ber);
+		n += scnprintf(&buf[n], PAGE_SIZE - n, "\tts_per = %-5d\n",
+			      p->layer_info[i].ts_per);
+		n += scnprintf(&buf[n], PAGE_SIZE - n,
+			      "\terror_ts_packets = %-5d\t",
+			      p->layer_info[i].error_ts_packets);
+		n += scnprintf(&buf[n], PAGE_SIZE - n,
+			      "total_ts_packets = %-5d\t",
+			      p->layer_info[i].total_ts_packets);
+		n += scnprintf(&buf[n], PAGE_SIZE - n, "ti_ldepth_i = %d\n",
+			      p->layer_info[i].ti_ldepth_i);
+		n += scnprintf(&buf[n], PAGE_SIZE - n,
+			      "\tnumber_of_segments = %d\t",
+			      p->layer_info[i].number_of_segments);
+		n += scnprintf(&buf[n], PAGE_SIZE - n, "tmcc_errors = %d\n",
+			      p->layer_info[i].tmcc_errors);
 	}
 
 
-- 
2.43.0